That One Boss/Megaman

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You'll wish you just had to fight Air Man after dealing with these guys.

Mega Man stands as a shining example of classic Nintendo Hard. These guys are the reason why. It doesn't matter if you've got the select trick or a folder full of Program advances, these mechanized murder Masters are coming for you.

Just keep in mind that Bonus Boss is banned from being That One Boss. It's optional and you know it's overpowered, so nothing prevents you from not fighting it.

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Mega Man (Classic series)

• It should be noted that the Mega Man Anniversay Collection features an easy mode that covers the first seven games. The NES games benefit with Mega Man's defensive and specials weapon power being upped by 50%, buster shots do an extra unit of damage, while 7 doubles the power of every weapon. The bosses can still be a pain in the ass though.

Mega Man 1

• Elec Man is possibly the hardest boss to kill with only your pea shooter in any game. He runs around the arena like he's on crack, throws nearly impossible to dodge lightning bolts at you and can kill you in three hits! Granted he's very weak to the Rolling Cutter (Cutman's weapon), but if you didn't quite figure out that bosses have weaknesses...
• Fire Man, mainly because his fire pillar attack is very powerful and you have to have perfect timing to jump over it. Also he spams this move like there's no tomorrow, so even having the Ice Slasher isn't going to guarantee you victory.
• Ice Man's a boss who should be easy on paper, seeing as how he sticks to a strict attack pattern that he never deviates from. But in practice he's surprisingly hard: his Ice Slashers are huge and since the floor of his arena is icy, you have slippery ice physics to wrestle with as well. And if that wasn't bad enough, his attacks are powerful enough to kill you in three shots meaning that there's very little room for error when fighting him.
• The Yellow Devil from Wily Stage 1. Many gamers had lost a good chunk of their childhood trying to get past this shining example of Nintendo Hard. Unless they cheated.
  • The worst part about the Gamecube version Anniversary Collection is that the glitch that makes the Yellow Devil easy to beat was drastically changed (the timing was changed to make it less effective if you knew the change, worthless if you didn't), thereby making the fight that much more difficult.
  • Then the Rainbow Devil shows up in Mega Man Zero. It's just as cheap as previous models. It has an especially annoying attack where it bounces around the room, splits into two parts, then into four before finally reforming. It also has a punch attack that crosses nearly half the arena and a projectile attack that makes nearly the entire ground a danger zone. Good times. Thankfully, the redux in Zero 2 is actually somewhat easier.
  • And there was also Dark Moon, the Devil-type boss in Mega Man V for the Gameboy. He's hell to beat with his own weakness, the Photon Missile, and his separation attacks, the top two rows would bounce down in order to try to kill you.

Mega Man 2

• Air Man, whose hard to dodge tornadoes that deflect your bullets make him an infamous example of this trope.
  • Strangely, this is a reversal of an earlier viewpoint - Air Man used to be considered almost as weak as Bubble Man, and a good boss to start the game on. This may in part be due to the American manual having a walkthrough for his stage.
  • Note that the Japanese original of the game (which spawned this particular bit of Memetic Mutation) only has Hard mode. This means you do half damage to all bosses, and some enemies too. The US version was made easier be default, and Air Man is affected by this. On the US version's Normal difficulty you can damage him much faster than he can damage you, but you actually have to learn to play on the Japanese version (Hard mode in the US).
• Quick Man's level is hard enough, but the robot himself doesn't let up. He is incredibly fast, and while his Quick Boomerangs are annoyingly tough to dodge, its his collision damage you should be worried about because he can easily wipe out a third of your health just by running into you! Making things worse is that his weakness is the Time Stopper, but it only takes out half his health meaning that you'll have to fight him with your buster regardless. And since the Time Stopper's also invaluable for avoiding the insta-kill force beams throughout his level, its easy to waste its ammo before even getting to him! Frustratingly, Quick Man is supposed to have an easy attack pattern to play around, but a bug in his AI derails it and turns him into an unpredictable spaz which is the main reason for his infamous difficulty!
• Wood Man is a good example of just how flexible Mega Man boss difficulty can be. With the Atomic Fire he's a sinch, but without it he becomes a lot scarier, because in between his protective Leaf Shield and impressive defenses, it takes a long time to whittle him down with your buster and Metal Blades. The leaves he drops from the sky also have deceptively big hitboxes, requiring pixel perfect gameplay to avoid getting hit while you're dodging, which means that unless you're really on top of your game, Wood Man will easily outlast you in a war of attrition. So yeah... don't fight him first.
• Crash Man. His jumping is tied to your firing button making it almost impossible to actually hit the guy on a first glance. However you can kill him in one shot if you know what you're doing.
• The Mecha Dragon in the first Wily Fortress stage, who doesn't do anything too ridiculous but makes up for it with technically being able to kill you in one hit since the recoil from his attacks is enough to knock you off your tiny block platforms and drop you into a bottomless pit. Someone even wrote a blog entry in which this boss fight was compared with a major real-life hangup. Made worse in Anniversary Collection, which removed an exploitable bug to make yourself invincible during the fight.
• The Boobeam Trap, The turrets with blindingly fast shots from the walls heading straight for you every three seconds or so. It's the other boss in Wily's Fortress that only has one way to damage it. And the kicker? You only have seven uses of the weapon maximum. Five to actually destroy them, and at least one to break barriers blocking the others. If you don't make clever use of Items and/or accidentally miss a shot or two then you will not be able to defeat this boss. And since you don't get energy refills after death you either need to take forever restocking energy off the few enemies or just game over entirely and restart the stage. There's a reason why practically every MM 2 romhack out there, even the obscenely hard ones, generally make this boss easier.
• This game's incarnation of the Wily Machine is a huge step up from the first game's, and is a lot tougher than nearly every version that came after. It starts off as an easy fight, but when the second phase starts Wily decides that he's done playing fair and begins shooting gigantic bullets that are deceptively hard to dodge. Hitbox dissonance doesn't even begin to describe it, because you'll get hurt when you're nowhere near the bullets. Thankfully, you can still dodge them when they're spaced apart... unless he fires a volley. And in that case you're screwed because when several shots are bunched up together, they are IMPOSSIBLE to dodge, meaning that the player is better off playing sloppily and damage racing Wily to victory since caution can only get you so far against him. It's so bad that Let's Player Roahmmythril found him impossible to beat during his Mega Man perfect run videos unless he broke his "uncharged Mega Buster only" rules, as seen here.

Mega Man 3

• Shadow Man. His attack pattern isn't hard to learn since he always jumps three times (Or two times, but only during his first attack) and either slides into you or throws a few Shadow Blades. The problem is that both attacks come out really fast and give you next to no time to react, and there's no tell for what attack he's going to do which makes it easy to jump right into his Shadow Blades on accident. His weakness is also aggravating to use against him, because the Top Spin is not only a melee weapon in a series that is not made for melee combat, but it burns through energy fast and if you aren't careful using it, you can easily drain it of all its ammo in one go while Shadow Man's still got plenty of health left.
• Needle Man's also pretty bad. You'd think that a robot as heavily armored as he is wouldn't be as spastic as Quick Man, but lo and behold: he leaps and bounds throughout the stage, making it hard to hit him while he either showers you with needles in tough to dodge patterns, or pounds you with the deceptively fast needle press on his head for massive damage. The Gemini Laser isn't even guaranteed to take him down, because if you miss your shot (which is easy to do) because he leaps out of the way, you better hope and pray that it hits him on the rebound because as long as the Gemini Laser is active, you can't fire another and you can't even pause to pop an E-Tank or switch back to your Mega Buster.
• The Doc Robot takes the abilities of ALL the Robot Masters from 2 (You fight two per level, and they make you play through the four harder stages revamped to be harder). If you thought dodging Wood Man's swirling leaves was bad before, try it when they are even larger! Try fighting Crash Man without an attack that can shoot up! TRY FIGHTING A LARGER, FASTER QUICK MAN! Geez...
  • Oh, and since it's Mega Man 3, you now have to try and figure out which weapons the Mega Man 2 robots are weak against, all over again. Almost none of them are intuitive either.
  • Bonus points for the Wood Man version, as the Leaf Shield has both larger leaves and larger shield radius -- large enough that you almost need Rush Coil to get over it (which consequently smacks you into the leaves coming from above).
    • Further bonus because, even when you do figure out their weakness, they aren't as effective as their weakness was in Mega Man 2 (nothing can break through the Leaf Shield, for example), and they still do way more damage to you than you can do to them.
• This game marks the first time that the dreaded Yellow Devil returns. Sure, your new slide ability makes it easier to dodge his body parts when he splits up and reforms, but he makes up for it by attacking you a lot more when his weakpoint is exposed, making it hard to safely hit it. He can also send his sections bouncing across the arena, where they have Hitbox Dissonance out the ass and will hit you even if you clearly dodged them.
• The Holograph Mega Mans (Yes, that's their actual name. Blame that on the game's sloppy translation) can enter this status if you aren't able to kill the real one at the start of the battle. Because once he and his clones start switching places, it becomes aggravating to get a hit on him because thanks to the platforming you have to do to find the real one as well as the barrage of buster shots they send your way, it becomes a vicious cycle of trying and failing to locate and hurt the real Mega Man while you get shot to death in the process.

Mega Man 4

• Bright Man, who's basically a much tougher version of Flash Man from Mega Man 2. Flash Man ran around in a set pattern most of the time, and during the rare moments where he'd freeze you with Time Stopper you were completely safe as long as you were in the air. Bright Man however is tough because when he freezes you with Flash Stopper, he seems to always follow up by jumping straight into you no matter if you're in the air or not. And in a game where most of the bosses deal a crap ton of collision damage, that's a very scary combo and can lead to a number of cheap deaths. And even with the Rain Flush on your side, the huge amount of cooldown between uses still give Bright Man plenty of time to pound you into paste.
• Dive Man, mainly because he's quick and aggressive, and is another boss who takes advantage of Mega Man 4's ridiculous collision damage by forgoing his homing torpedos and simply ramming you with his Psycho Crusher-style body slams. Jumping over him isn't a safe bit because he's scary good at stopping his charge short and catching you on the way down, and having to deal with the floaty water physics while he can zip around unoppossed doesn't help. What's really scary about Dive Man though is that he becomes harder if you use his weakness, because the Skull Barrier is so small that colliding into him with it pretty much means your going to take huge damage in the process. It doesn't help that the Skull Barrier is considered to be the worst shield weapon in the series, and a big part of it is that it's the one shield you can't throw at the enemy.
• The first battle with Wily is absolutely brutal if you don't realize you can pre-detonate the Drill Bomb and explode it to hit Wily's weak spot: any other weapon either does little to no damage and if you don't detonate the drill before it hits the weak spot, it'll just bounce off. He fires a constant barrage of huge fireballs bigger than mega with no discernable pattern. And yes, the weak spot on his machine is just a bit too high to reach with a straight shot at your apex. Pharaoh Shot which can be aimed upwards, doesn't work. If you don't know how to use Drill Bomb properly, you're going to have to self-terminate on that level over and over until you've stockpiled all 9 energy tanks if you want to win.

Mega Man 5

• For the most part, Mega Man 5 has tons of easy bosses. However, there's still one that stands out from the rest of the other Robot Masters, and that's Charge Man. Mainly, Charge Man's difficulty stems from his erratic movements which make it very easy for him to run right into you while you're attempting to jump over him, and his collision damage hurts quite a bit. Then, there's the fact that he's very prone to going berserk by turning red and launching coal into the air, then usually following up by ramming you. He can't be hurt at all during this state, so it's very easy to waste a charged shot on him while also being nailed by all these attacks he's throwing at you at once. And he's yet another Robot Master who's weak to a terrible weapon that's awkward to use against him, this time the infamous Power Stone.
• Dark Man 3 is a lot tougher than the other Dark Men, mainly because the three paralysis-inducing rings he shoots are tough to dodge, and when you get hit by them you're helplessly frozen until he hits you, usually by launching himself right at you which deals a ton of collision damage.
• Big Pets from Wily Stage 1 is tough mainly because its fight is a delicate balancing act between shooting its body segments so they launch themselves at you, making sure you land on top of them so they don't hurt you instead, avoiding the annoying enemies its constantly sending your way, and shooting its head and dealing with its deceptively small hitbox. Its very easy to rack up tons of damage in this fight, and even those who have an easier time with it cite it as a Goddamned Boss for the sheer tedium of it all.

Mega Man 6

• The Power Piston from Mr. X Stage 2 is a nightmare and a half. The whole battle consists of you dealing with nightmarish projectile spam where it's constantly pelting you with bullets while dropping boulders on your head in unpredictable patterns, and the shrapnel from when they explode still hurts you! It's also attached to the wall and constantly moving out of your reach, and its weakness to the Silver Tomahawk doesn't make things much better since its arcing shot tends to miss its mark more often than not. And the cherry on top of the shit sundae is that the constant loud explosions during the fight will seriously get on your nerves.

Mega Man 7

• Slash Man, who's fast, strong, and can cripple you with the red goo he drops from the ceiling, which will make it impossible to jump slide or shoot if it lands on you or immobilize you entirely if you step in it. Said goo drips down in random patterns that leave you with a split second to dodge, and failure to do so means you're doomed to take an attack from Slash Man if you want to regain control over yourself again. Not helping matters is the fact that when you hit him with either of his weaknesses, he'll go straight for the ceiling and try to drop goo on you, meaning he's a rare boss whose weakness makes him harder to fight!
• Freeze Man is also tough thanks to his fighting style revolving around freezing you and leaving you helpless to dodge him. Even when you get the timing of his freezing attacks down, the icicles he summons give you next to no breathing room thanks to randomly dropping in one of two patterns that you just can't predict.
• Guts Man G of Wily Stage 1, who is the deadly end result of Guts Man taking several levels of badass. His Super Arm now drops a massive boulder from above that has a good chance of crushing you outright, and if you dodge that he follows up by flinging it against the wall which requires near-perfect reflexes to dodge. And if that wasn't bad enough his other attack is to simply charge you, and do a huge amount of damage by slamming you into the ceiling. It can be stopped by shooting him to slow him down until he gives up, but not only does that require near-perfect reflexes to hold him back, but it's not intuitive the first time and can leave even experienced players baffled since no other time in the battle do your body shots push him backwards.
• HannyaNED, the floating oni head of Wily Stage 3. The screen autoscrolls, it has a plethora of hard-to-avoid attacks such as barrages of bombs and Eye Beams, and its weak point is very small and can only be reached by jumping on the missiles that only stay on screen for a fraction of a second.
• The final boss also fits here. He is definitely overly hard by the standards of final bosses for the Mega Man series. His weakness, the Wild Coil, is (as per the tradition) difficult to hit him with. His main attack is shooting four elementally charged orbs in your direction, then they stop in mid-flight to adjust their path. And they hurt: the fire orbs will slowly burn off huge amounts of HP while completely immobilizing you, and the ice ones make up for their lack of damage output by leaving you helpless against Wily's ground-traveling sparks, which DO hit hard. The yellow shots on the other hand are weaker and don't have any weird effects, but even those add up before too long. Fortunately, he's at least damaged by some other, easier to hit with weapons, such as Freeze Cracker. Word of God says that even the developers found this one impossible without E-Tank usage. Even has some Lampshade Hanging, in which Mega Man attempts to kill Dr. Wily following the battle.
  • This battle is so bad that the creators actually used it again as the final battle in Mega Man 8 and significantly lowered the difficulty. When a final boss battle is so tough, that the programmers actually redo it in the next game just to apologize to fans that struggled getting through it initially, it definitely qualifies for That One Boss.

Mega Man 8

• Astro Man, if you don't know the way to dodge his Astro Crush or use the Homing Sniper to immobilize him on the ground, he will destroy you easily and quickly. Oh yes, and he's also the boss of That One Level, so have fun with that.
• There's the first Wily Fortress boss, that can only be hit by the Mega-Ball, a weapon that has to bounce off of the wall up to the ceiling at the right angle to hit the boss. It doesn't help that its level is pretty tough to get through normally.

Mega Man 9

• Tornado Man, mainly because his attacks are very difficult to dodge and his weakness weapon is a ground based attack while he spends most of the time flying in the air.
• Concrete Man is a pain; he hits very hard, his weakness, Laser Trident, doesn't do much damage to him, and he has an unavoidable charge attack if you're trapped in concrete. While the Trident can break the blocks, it doesn't work if you're stuck in it--and they travel diagonally from the air and are very fast.
  • The third elephant mini-boss in his stage (Paozo) is as annoying as its master. You could easily cheese the first one entirely and the second isn't much tougher, but the third fights you in a room with bottomless pits in the ground. And since you have to fight him while dodging the ball he keeps shooting at you and sucking back in, while also fighting the suction as it tries to drag you into the pits... yeah, its problematic to say the least.
• What's worse than one Devil? Two of them at the same time. Both the yellow and green devils sends blocks of each other right at you at the same time. The pattern is actually easier this time, however, but the core flying out to switch blobs in the middle of it all makes it a little annoying. Inti Creates, you clever bastards...Fortunately, the pause-glitch works on it.

Mega Man 10

• There was one character who both inverted this and played this straight depending on the circumstances. I'm talking about Strike Man, who is the easiest robot master to beat with his weakness weapon the Triple Blade, but the hardest to beat if you don't. He's weak to one of the most powerful weapons in the game, so beating him with it is a snap, but the reverse is also true, as without said weapon this guy's a nightmare to face. His weapon can bounce off the wall and he can have multiples of them at once. It doesn't help that he is also very fast, very strong, and the boss of a level who has not one, but two annoying midboss fights. I hope you have his weakness weapon, or a lot of E-Tanks, because if you don't, well good luck dealing with him.
  • If you're using Proto Man, you can at least slide under him when he bounces toward you, unlike Mega Man. This is also a double-edged sword however since Proto Man has half the defense of Mega Man, and therefore takes twice the amount of damage if he gets hit, so hopefully you're good at dodging.
• Blade Man, mainly because he's like a powered up Shadow Man from Mega Man 3 and even faster and stronger with multiple projectile attacks that are tricky to dodge. He can also negate his weakness weapon the Commando Bomb if he swings and hits it before it can detonate right next to him, and the bomb itself does minimal damage, meaning the shockwaves from the explosion have to hit Blade Man before he jumps to the ceiling or another wall.
• Pump Man, mainly because he controls the water current on the floor to work against you and make you even slower than you already are which make dodging his attacks almost impossible, especially as Mega Man who can't slide in this version. It doesn't help that he can negate his weakness weapon the Thunder Wool if he times his attack correctly.
• Solar Man is pretty much impossible without his weakness weapon, the Water Shield mainly because he can absorb the shots from your Mega Buster and shoot a huge burst of energy right back at you when he has enough power. Good luck if you take him on first, especially since his minibosses are just as tough.
• The Block Devil. Imagine, if you will, an unholy union between the Pico Pico Master (2nd fortress boss from 2) and the Devils' penchant on splitting and reuniting in definite patterns, throwing in a weakpoint that stays on screen only 1/3 of the battle and a bottomless pit that becomes a Kaizo Trap if you happen to defeat the boss standing on/over a purple block. Oh, and his weakness involves one of the most awkward weapons in the series!

Mega Man 11

• The game really seems to want you to fight Block Man first: he was the first Robot Master to be revealed, his stage was the first to be shown off, and he's really prominent in the game's intro. And he seems easy enough when you fight him... until you knock out about a third of his health, then he pulls the rug out from under your feet by activating his gear change ability. Then with a boost from the Power Gear, he gets a new health bar and becomes a humongous stone monster that puts up a way better fight. His weakpoint is hard to hit, and his attacks are now devastatingly powerful, long-reaching, and come out surprisingly fast. Once you wipe that out, he has a third phase that's admittedly easier, but since you're likely to be pretty banged up from fighting his giant form, he can easily finish you of thanks to how fast his flurry of blocks comes at you. He's a lot easier to beat with his weakness, but since the game is practically begging you to fight him first it's jarring to see him put up this good of a fight for an unofficial first boss. And it doesn't help that the boss he's weak to also qualifies as That One Boss, as does the boss he's weak to...
• That aforementioned boss, Blast Man, is basically Bomb Man but strong. He's agile as hell, and the bombs he fires take up a good chunk of the screen. He can even fire them while jumping, making them awkward as hell to dodge. And if that wasn't bad enough, when he uses his Power Gear ability they grow HUGE and require damn-near pixel perfect dodging to avoid.
• He's already the boss of That One Level, but Torch Man doesn't show you any mercy. His basic attack is fireballs that absorb your shots, but his deadliest attacks revolve around martial arts: he can suddenly dash forward with little warning and kick you across the screen or jump into the air and launch himself at you with a brutally fast divekick, and both attacks have ridiculous knockback that can ruin your flow. And while his Power Gear (noticing a pattern yet?) boosted flame wheels are slow and predictable, they're so big that jumping over them is no easy feat. Overall, this guy's a real pain in the ass, and it doesn't help that he can lure you into a false sense of security by sticking to a pattern, only to break it by dive kicking you in the face. Grr...
• Guess who's back?! The Yellow Devil, and he's the boss of the first Wily stage again! He actually has the exact same attack pattern as he did in Mega Man 1 meaning that veterans will be able to dodge his notoriously fast body segments when he splits up and reforms, but even they'll be thrown for a loop when he activates his Speed Gear. Suddenly, he splits into nine tiny devils that rocket around the screen like they're on crack in tough-to-dodge patterns. The collision damage he deals is nasty, and it doesn't help that it's tough to hit him with his weakness, the Chain Blast, due to how slow it is and how briefly his weak point is exposed.

Mega Man and Bass

• This game is notorious for Dynamo Man, who likes to hop into a recharging rig in mid-battle. By the time you break it, he'll have regained at least a third of his HP (and he'll happily refill completely if you take long enough).
• Just as bad as Dynamo Man is Burner Man, who resides at the end of That One Level, and has several attacks that deal a lot of damage as well as one that holds you in place as he has his way with you. His Wave Burner is also capable of deflecting shots, and he likes to back you into a corner with it. Fighting him with his weakness, Cold Man's Ice Wall, he becomes somewhat of a Puzzle Boss, having to use the Wall to push him into the spikes on either side of his arena. Thing is, there are only certain frames that he's vulnerable to this, any other time and he'll bust right through it, and you've wasted your ammo. If you mess up too many times, it's easy to run out of ammo, and be forced to go through his agonizing stage all over again.
• The second boss fight of the second fortress stage. It's above a bottomless pit, you have to navigate randomly appearing platforms that the boss can destroy, one of his attacks will blind the screen, and is just a pain overall. You will fall into a bottomless pit and die multiple times even if you utilize a few weapons based tricks to stay in the air and/or keep damaging it.

Mega Man Powered Up

• CWU-01P, especially when playing as Rock/Mega. His main way of hurting you is Collision Damage. Sounds easy, right? WRONG! At least on the aptly-named Hard Mode, he's damned fast. And as the aforementioned Joke Character, you can't hurt him without getting right in his face and kicking him enough to first get rid of his bubble shield, then once more to actually cause damage. Oh, and just for good measure, he does also have another attack -- a frickin' laser beam!
• Also, if you're playing as a Robot Master, when you have to fight the Master who's weapon is strong against you, good luck.
  • Special mention must go to fighting Cut Man as Bomb Man, as all of his attacks can destroy your bombs. In other words, the only way to do any damage to him is to throw a bomb behind him and hope that he doesn't jump away before the bomb explodes. Lather, rinse and repeat 15 more times.
  • Anything with Oil Man. His weapon, a piss-poor slide kick you can only activating by placing a single oil slick on the ground, is terrible. It's a melee weapon in a franchise where they tend to suck, and just about every boss can effortlessly avoid getting hit with it.

Mega Man X

Mega Man X

• The Bosspider, due to the speed she moves at, the difficulty of quickly figuring out where the boss will end up depending on what pole she appears on and where the pegs she moves along appear and the timing needed to hit before she regains its invincibility. And then she Turns Red.
• Storm Eagle is hard to hit in between attacks because he is about half way up the screen. When you fight him, there is a doom pit on either side. He has a number of hard to deal with attacks, but most of the time just flies around randomly, crashing into you.
  • Try fighting him without getting the Dash Boots first, hope you have some good aim when he's dive-bombing the screen.
• Armored Armadillo has 3 strategies: guarding, bouncing off the walls and shooting his energy shots. He's invincible when ever he isn't shooting at you, as he will most likely block your attack. Guess what he decides to never do 90% of the time.
  • Now try fighting him on Maverick Hunter X's Hard Mode, where he picks up an attack where he bounces off the walls and fires off bullets in four directions. Even if you use the Electric Spark to take out his armor, it's still hellish.
  • Heck, try fighting Armored Armadillo WITHOUT Electric Spark. Even a fully charged X-Buster shot won't even scratch him.
• Launch Octopus. He dishes out homing torpedoes like candy and More Dakka is his trademark. When he's not firing torpedoes at you, he's jumping clear across the arena right on top of you. And to make matters worse, he also has a nasty attack called e-drain where he creates a whirlpool that pulls X into his grasp. Oh, and guess what it does when he grabs you.
• Boomer Kuwanger is the one boss that is almost impossible to beat without his weakness weapon if you don't know what you're doing. You can't just get lucky and pull off a victory with him considering that he constantly teleports and tries to grab you, then slams you into the ceiling For Massive Damage

Mega Man X2

• If you collect all of Zero's parts from the X-Hunters, then you'll be able to skip the battle against Zero at the end of the game. If you don't, you're in trouble at the end of the game before you battle Sigma. The only weapon that really hurts him- the Speed Burner- is hard to hit him with, and his attacks are hard to dodge. And after you've beaten him (probably draining all your Sub-Tanks in the process), you still have to fight Sigma. The moral of the story is to get all of his parts, no matter how hard they are to get early in the game.
• Violen is the worst of the three fights you have to do to get the Zero Parts, considering he liked the idea of Armadillo's invincible attacks, but decided to make them even less predictable.

Mega Man X3

• Crush Crawfish, mainly because if he grabs you with his huge pincers and lives up to his name, he does so much damage it's not even funny.
• Byte isn't all that difficult if you know what you're doing, but he uses an absolutely cheap and never-before-seen gimmick to utterly crush the unprepared. He throws a device on the wall that slowly repels X. He'll charge at you shortly after it attaches. If he hits you, he'll punch you into the ceiling, wait for you to fall, punch you into the opposite wall, and repeat the pattern. You cannot break free from the punch combo, and it's his one and only attack, so he can easily loop it until half your health bar is gone. He's too big to jump over, so you have to either execute a well-timed up air dash or dash-jump at the wall and use the split-second of hang time you have to dash-jump over him. Oh, and whenever he hits the wall, if you aren't in mid-air, you're on your butt, so you better have hopped over him before he hits.
• Sigma and Kaiser Sigma. Sigma's swapped out his Z-Saber and Wolverine Claws for a Captain America-esque shield, which defends him from all attacks as long as it's bared. His main attack consists of spraying fireballs all over the place, which have an unpredictable pattern and do huge damage. They can be avoided by air-dashing to the wall Sigma's adjacent to, so of course he begins throwing his shield to knock you out of the sky. And when you do bring him down, you get to face Kaiser Sigma, who takes up a quarter of the screen, fills another quarter of it with floating mines, has a weak spot about the size of a pinhead, and keeps his back to you for half the match. Oh, and when he's dead, you have to do an escape segment with rising lava eager to nip away your last few bars of health while his virus form harrasses you. He may be the final boss, but he's considered to be easily the worst of all the SNES games.

Mega Man X4

• Magma Dragoon considering he has both the fire based Hadoken (Fireball) and Shuryuken (Dragon Punch) and loves to constantly spam these moves. This isn't even the best part as when he gets hurt enough he'll shoot out a large stream of fire, or summon a fiery meteor storm that is pretty much impossible to dodge. This is take Up to Eleven with Zero who has to get up close and personal, unlike X who can easily fight him from a decent distance away.
• Sigma's an exhausting grudge match, with three stages, the last consisting of two separate bosses, and no breaks in between. The first form goes down easily enough, but the second delights in chasing you around with his Sinister Scythe and filling the screen with projectiles, and the third? Each form stays on screen for maybe thirty seconds at a time, and alternates with three robot heads who try to knock off bits of your health and never stay dead for good. One of the two forms is prone to busting out a nasty laser attack with maybe a second's window for dodging, and the second has a nearly unavoidable garbage-spray and an attack that can knock you into some insta-kill spikes. And while X can tear through the first two forms with ease and at least keep the last at a safe distance, Zero has to deal with these things up close.

Mega Man X5

• Duff Mc Whalen, who's one of the biggest mavericks ever is basically like a whale version of Burst Man from Mega Man 7, has a very difficult attack pattern to dodge, and when he Turns Red, he actually tries to push you into spikes for an instant death which means you have to fight against him blowing you back and hitting him without taking too much damage or getting hit by the spikes.
• If you thought Storm Eagle was bad, The Skiver/Spiral Pegacion is a nightmare, boasting the same sort of attacks, but all vastly more difficult, coming from all directions at high speeds. Oh, and making him a standout from every other boss in the entire series, he does not have an actual weakness to a specific power. Instead, he can be frozen with the timestop power, which doesn't last long enough to punch off a decent portion of his health.
• Black Devil in the first Fortress stage is hard for X, but a NIGHTMARE for Zero. Besides a very hard-to-dodge spam attack, his weak point is his eye, which fires yellow orbs at you, and the most effective attack against him is lightning. X has his buster and Tri-Thunder weapon, both of which are ranged, but Zero has to use his saber and the E-Blade, which he slashes upwards while moving forward slightly. This means he has to get practically in the boss's face to use it, but far enough away not to touch the body (which deals massive damage). Add to the fact that sometimes the eye appears in a place which you plain can't reach with the saber, and you get a very difficult boss for Zero to counter.

Mega Man X6

• Infinity Mijinion, whose main gimmick is cloning himself. His clones have the uncanny ability to get in your way a whole bunch until you forget which one's the real one. It doesn't help that even getting to him is a huge problem because the entire stage is spent fighting a giant miniboss, which is no walk in the park either. Heck, this is a case in which using the boss' weakness probably makes the battle harder. Trying to even hit Mijinion with the uncharged Guard Shell is difficult, if only because it only works against one of his attacks (which is barely used, mind you), but if it does hit, it creates another clone. It wouldn't even be that bad if the clones didn't have so much health, usually taking three charged normal shots to destroy.
  • This is taken Up to Eleven with Zero if Infinity Mijinion does his ultimate move and hovers in the air in the middle of the room dropping an endless amount of clones. X can at least stay on the wall and shoot him, but Zero has to do a huge wall jump from the top of the wall and strike him in midair.
• DESU BORU!! Er... High Max. AKA 'Assclown'. "Hmm... What's this glowing crystal-like thing here? Oh, wow! Haven't been here before. Guess I can fight the main boss later. Huh? A door? Must be the main boss. Wait a minute... Pfft! This guy's no problem... Oh, wait. I don't have any weapons on me, and I need them. Like, at all. Time to kill myself!"
  • Plus, if you take him on with Zero, his only weakness is a very short range attack, and then you still need to slash him to do damage. Be sure not to touch him though! Then, he Turns Red and starts firing off projectiles four at a time, which, if you weren't absolutely careful before, will probably kill you very quickly.
• The Sub Boss of Blaze Heatnix's stage. Which you fight 5 times over the course of the entire stage, with exactly 1 segment that doesn't involve fighting it or the actual boss. The worst offender is the part where you fight it while forced-scrolling upwards on very small footholds. Which the sub-boss is bigger than. It doesn't help that there's insta-kill lava covering half the fucking screen.
  • Heatnix's miniboss is cake if you've used X to beat Metal Shark Player or used Zero to beat Infinity Mijinion first. Slap it with X's fully charged Metal Anchor or Zero's Giga Attack twice and it's gone. The real bastard is Gate. Invulnerable to all your attacks, so you have to turn his back on him, and tends to fly right into you. His attacks are ALSO hard to turn back on them, since they need to be level with him, and then hit him in the face as they break from damage. The most damning part of the fight is the arena. There is no floor, so you're liable to fall to your death more often than not. The only good thing about this battle is that you freeze in place when Gate runs out of health, so there's no risk of falling to your death after beating him senseless.
• The Nightmare Mother(FUCKER!!)... Good God. On Normal difficulty, this boss fits her name to a damn tee. On Xtreme, she cranks this up to insane heights. Both cubes move at an accelerated speed even at full health and can change direction whenever they like, all while constantly firing projectiles at you until they stop. And if they do stop, you better hope the gods are smiling on you, since her attacks can be used by both eyes and combine sickeningly. Each eye can release shockwave-producing projectiles, raining fireballs, floating orbs that shoot lightning or even set the floor on fire. Two out of four of these attacks reduce your dodging room severely, and if they ever set the floor on fire AND shoot the lightning orbs, then you better. Fucking. Pray.

Mega Man X7

• Snipe Anteator. On paper, his weakness was the "Moving Wheel." In the game, you could barely get said weapon to hit him. Even if you could, it actually did LESS damage than a fully charged X-Buster. Translation: Just use X already. Oh wait, you have to unlock him first! On top of that, he doesn't have a hitstun animation, meaning that he can counter your attacks as they hit him.
• Then there is Flame Hyenard. You had to damage a mech travelling over hot lava so you could get to him. This is easier said than done since the camera can screw you over. Then you fight Flame Hyenard. He splits himself into clones that shout "BURN! BURN TO THE GROUND!" The weapon he's weak against actually works, but if you're using X or Axl, you'll run out of ammo long before he is dead. And he has a Scrappy Level to boot!
• And then there is Red. If you don't have Zero, good luck to you. You have to target Red from a distance. Since the camera enjoys screwing you, this becomes a problem. Dodging his attacks is problematic because you're not fighting on solid ground. You're fighting on platforms with a hole in between each one. Fall and you die. Get hit while jumping and you will die. He constantly teleports around on those platforms and there is no way to predict where he will end up. The only way to finish the fight quickly is to use Zero and take Collision damage while slashing him.

Mega Man X8

• Bamboo Pandamonium. He's big enough that you can't get behind him without taking a hit, and has attacks that take up big chunks of the screen. Also, his desperation attack hits like a train and comes with virtually no warning. It's more bearable with the Ride Armor...What's that? You didn't know that you could take it with you? Too bad! And you don't have access to it at all in the Boss Rush, so good luck with that.
• Lumine. He comes after That One Level, and is fought directly after Sigma, who's hard enough to begin with. He has two forms; the first one uses the desperation attacks of the first 8 bosses except some are modified to last longer; when Burn Rooster's attack comes out, it lasts for the duration of the match. In other words, once it happens, you can't use the walls to dodge his attacks. Additionally, he himself is always moving, making it hard to hit him. Once you've drained his health, he enters the second form, which has a multitude of laser attacks (one of which lasts a long time and then comes back in reverse), has no weakness and is difficult to get a bead on. But the real hell comes once his health dips low and he uses Paradise Lost; if you don't kill him in the next 30 seconds, GAME OVER. No continues, nothing; you're done. Oh, and did you know you had to have Axl finish him with a Doubleteam as a prerequisite for the secret ending?

Mega Man Legends

Mega Man Legends

• There are two times in the game where you are forced to fight from a slow-moving vehicle and defeat several enemies and then a boss fight, while protecting your vehicle from the attacks. If the vehicle is destroyed, it is an automatic Game Over.
  • The first one is from a boat, and you're fighting several submarines and a few Draches, which can shoot torpedoes at your boat. After that, you fight the Balkon Gerät, a giant frog battleship-mecha, which will merrily chop your boat to pieces if you can't dish out damage fast enough.
  • This is made worse later with the Flutter. You have to fend off several Draches, the Gesellschaft itself, and then the Focke-Wulf, Tron's personal attack aircraft. The Focke-Wulf is especially nasty, the attacks that don't hit you WILL hit the Flutter. Unless you're specced for long-range damage output, you're not going to have a fun time.
• The Karumuna Bash trio, three doglike Reaverbots in the Clozure Woods Sub-gate. Those things are nasty if you're not Crazy Prepared for them. They all attack you at once and they are FAST. Their primary attack is jumping at you, which knocks Mega Man down and is possibly also a Camera Screw if you land right. Their other attack is to breathe fire, which instantly depletes your life meter's shield so you can take MORE damage from their jump attack.
  • Actually, these guys are some of the easiest bosses in the game. Just keep running in a circle while rotating the camera and firing off shots. It takes forever, but you can win without even taking damage.

Mega Man Battle Network

Mega Man Battle Network

• Most of the first game's bosses are fairly easy, but the same can not be said for MagicMan.EXE. He's constantly firing off a powerful ball of blue fire down the middle row, and is backed up by respawning Viruses that are quick to replenish when you delete them. He may not move at all from his starting position, but his simple fighting style is very effective, and it's easy to find yourself overwhelmed in a hurry.

Mega Man Battle Network 2

• QuickMan.EXE. The name alone should key you in to how annoying he's going to be. He is invincible at all times except during his attack frames, moves like a spastic monkey on crack, and his attacks are irritating to dodge, because Quick Boomerangs are really, REALLY fast moving It doesn't help that he's the second boss of the game, the first boss was a complete chump, and the next boss AFTER him isn't exactly threatening either, so he's not even really a Wake Up Call Boss... Worse yet, it's entirely possible for the game to be Unwinnable By Mistake here, as you can't leave his area (either to recover HP or improve your moveset) once you enter (but nothing stops saving...)
• 2 also had Napalm Man V3. He has 2000 HP, actually has moves that are difficult to dodge, and they pack quite a punch. Crystal Dragon Jesus help you if you have a Wood Style.

Mega Man Battle Network 3

• DrillMan.EXE makes the game a nightmare. He has lower HP than most bosses, but that's because frontal attacks have no effect - his drill is always blocking frontal attacks, so you have to go around the drill with Wide Swords and such. Only a handful of chips can bypass his drill, so good luck having one in advance when he appears!
• DrillMan.EXE's younger brother BubbleMan.EXE is seventeen times as annoying! The bubble spam, the bubble spam! Aaaaaaaaaah!
  • To elaborate, he never leaves the back row and the center tile on his side is a hole from which spout an infinite number of bubbles, which block shots and home in on you, always moving into your row so as to block your line of fire at Bubbleman. Since they're limited by number on screen if you stand there shooting them they'll just spawn faster. Meanwhile Bubbleman is using his own attacks on poor distracted Mega Man. Luckily the electric-element first boss has a megachip that can hit and stun Bubbleman no matter where he hides.
  • And that's not even taking into account BubbleMan v3, who almost ascends to Goddamned Boss status. You can't even find him unless you have less than 1/4 of your max HP. Frickin' bastard.
• KingMan is the second hardest boss. He hides in the far back row while his nearly invincible, regenerating chess pieces attack you and block your spaces. If that wasn't annoying enough, if you stay in the back row (the easiest way to avoid his chess pieces), Kingman has a "plan B" attack, where he summons some new chess pieces and permanently steals an entire row of your area. Not even Bass's auras can compare to this guy's cheapness.
• The mandatory BeastMan Beta battle is friggin' unfair. Beastman moves rather fast around the screen, and will leap into your side of the field to attack (he likes to go behind you). Now, hitting him isn't as hard as it sounds, but he still is fast and deals a lot of damage.
• Flame Man has two candles on his back row, each of which have about 20 HP or so, and revive after a short amount of time. They have different effects depending on their color, and if even ONE of them is Green, he's invincible. If one's Red, he recovers HP steadily, and if one's yellow, then fire appears in your area and limits your movement range. Even worse, he can have two of the same candle, which means he can be recovering HP AND invincible at the same time. And his attacks are designed to take advantage of this.
  • This is completely trivialized with Area-grab. You see, his attacks were all designed with the idea that you were fighting in a 3x3 area. That extra row means that outside of you standing directly in front of him, he can't even hit you. Granted this doesn't do much for your grade if you can't beat him in time but it pretty much nerfs him from a YMMV to Guide Dang It.
• Even among Final Boss standards, Alpha is ridiculously tough. For starters, to even fight the guy you need to defeat Bass.EXE who's quite tough in his own right. Then in the fight itself, you need to chip away at Alpha's torso with buster shots before you can actually deal damage via hurting the core, and doing so is frustrating since you constantly need to dodge a constant onslaught from his claws, which while they follow a predictable pattern, they're still likely to nail you if you're too twitchy in the fight. And if that wasn't enough, you're also bombarded by other nasty attacks such as a ludicrously powerful, very hard to avoid laser blast. And the kicker? If you lose to this guy, you get to battle Bass.EXE again before fighting him! Ain't life just swell?!

Mega Man Battle Network 4

• Duo's Meteo Fist attack, and by extension Nebula Grey's dragon attack can easily make the fight unwinnable if you don't have Air Shoes or a Panel Return handy, since your field is cracked to the point where you can't dodge anything.
  • That's not the only way the fight against Duo can become unwinnable. Thanks to the game's New Game+ structure you'll fight Duo in a "normal" playthrough with more-or-less the chips you'd get in the first third of one of the other games, and when you fight him on a New Game+ he'll have his health scaled up to truly ridiculous levels. A Marathon Boss is fine for a final boss normally, but problematic in the Battle Network series because no matter how long the battle lasts you can ONLY draw thirty chips. If you don't pack your folder with thirty of the most damaging chips/combos in your library (and then consistently hit with them, as they likely won't be the easiest to connect with), or throw too much defense in your folder, you will run out of attacks before he runs out of health. For the third fight you pretty much need a top tier combo folder out of a strategy guide just to deal enough damage, never mind actually fighting him with it. Oh, and if you're relying on drawing just the right combo in the same hand, for a PA or a powered-up megachip, you'll have to fight another boss right before him every time you get unlucky. Or miss.

Mega Man Battle Network 5

• CloudMan.EXE evidently took cues from Bubbleman.EXE. He stays in the back row, protected by clouds that periodically shoot electricity. The clouds don't have much health, but despite this can take infinite punishment from time-stopping Chips. He can also hide in a cloud while summoning a pillar of clouds that chases you around, and the pillar remains even after Cloudman stops hiding.

Mega Man Network Transmission

• BrightMan.EXE, the first boss to put up shields to your attacks. Whereas the previous bosses were dodging and slapping the boss hard enough before they got you, Bright Man will murder you if you try the tactics that worked on the previous bosses and indeed, some of the other bosses you can fight at the same time. And the bosses get craftier, more agile or with more invincibility shielding from there, making Brightman a Wake Up Call Boss.

Mega Man Zero

Mega Man Zero

• Aztec Falcon, the first mission boss is almost impossible the first time you fight him. You have no charge attack (unless you spent time grinding it out by going back to the Underground Base; if you're playing on Hard, you're screwed), he isn't vulnerable to combos, and the Z-Buster actually bounces off when the chance to shoot him presents itself.
• Phantom is spectacularly cheap compared to his fellow Guardians. Three of the Guardians have an elemental weakness which makes beating them fairly simple. Not Phantom. He's neutral, so it takes longer to kill him. Worse, the other Guardians can have most of their attacks interrupted. Only Phantom's dash attack can be interrupted. It is technically possible to interrupt his Doppleganger Spin technique with a charged blow, but for added cheapness Phantom will break the technique and strike you should you close in to attempt it. Speaking of the dash attack, he'll often do it until you hit him, and he charges to your position. If you don't hit him right off the bat, he'll get at least one hit in, maybe more if you don't score a knockback hit. Finally, his Desperation Attack makes him invisible, during which he'll throw kunai at you from random points on the screen. What's worse, he may potentially position himself above the reach of your weapons, or just plain above you. To top this, he has a Kaizo Trap ability in the second battle.
  • Phantom's caveat is that he's nearly impossible if you fight with the Z-Saber, but a total pussycat if you use the Buster. It locks him into his doppleganger attack and interrupts his dashes even at half-charge. On the other hand, he'll instantly counter at every opportunity if Zero tries to go samurai on him.

Mega Man Zero 2

• Phoenix Magnion is plain ridiculous. He has an arena which spews fireballs from the floor, for starters. You can arrange it so the floor is blocked the first time you fight him, but not the second. What's worse, he dodges every attack. He literally cannot be hit unless he's attacking. And when he dodges, he counterattacks with very wide-area abilities.
  • He's an Expy of M. Bison, which helps explain his difficulty (Of course). That huge fireball he "shoots" after dodging backwards is the Psycho Crusher. Hit the fireball (with him inside) with a thunder attack(It's your only chance of winning in Hard Mode!).
  • Also, Phoenix is purely reactive, which means that if Zero just closes the distance and waits for a second then he'll begin an attack without dodging or teleporting and leave himself wide open.
• Kuwagust Anchus on Hard Mode is just insane! Not only is he really fast and powerful (two hits = dead, period), but he's the boss of That One Level! And he has an attack which can't be dodged, meaning you have to get him to change his flight path. And the only way to do this is to either shoot him with the buster enough times, which takes better timing than God to pull off, or deflect him with the Chain Rod. As if you're just supposed to know this out of hand. And he'll keep using this attack till you die.

Mega Man Zero 4

• Kraft from Zero 4 is a nightmare to fight against. The grenades, the laser rifle that requires you to dash underneath it with split second timing, the giant knife that damages you as it throws you across the arena, the missiles, and the fact that he's one of the few bosses willing to get right directly up in your face on a non-scrolling single-screen battlefield are awful.
  • Making it worse is that you can't revisit stages. Couldn't find Subtanks or enough E-Crystals to upgrade your Cyber Elf? Too bad! Also, he appears after you've beaten 4 out of 8 stages. He also has no weaknesses. Some people were left with no choice but to restart the game.

Mega Man ZX

Mega Man ZX Advent

• The Spidrill miniboss! It breaks the floor (which, in addition to removing a quarter of your standing space, can affect whether or not you unlock a vital checkpoint so that you never have to do that again), the walls have got spikes on, it summons miniatures of itself, and it has an irritating tendency to spam a move that spins its legs around. The upgraded Spidrill Neo fight in the Quarry is comparatively easy for nixing the first two aspects and coming right after you unlock Model ZX.
• Chronoforce on Expert starts the fight with Time Bomb, and it never wears off, so he's always in turbo speed. What's more, you know that spreading icicle move he does that you were able to jump between on Normal? Now he shoots two sets of icicles, the second set covering all the angles the first doesn't, making a roughly 90-degree arc that's really tough to avoid whether you try jumping between them or dashing underneath Chronoforce to get past them entirely. And may God help you if you haven't figured out the trick to dodging his attack where he shoots a whole volley of potentially exploding icicles at you from the background, then rewinds them to hit you again.

Mega Man Star Force

Mega Man Star Force 2

• The Infinity bosses, particularly Cancer. They managed to take one of the (arguably) easiest bosses in the game, and upgrade him to have absurd speed and 2800 HP (!). On top of that, his claw attack is now so fast that it's basically an unblockable 200 damage unless you have an Invisible on you.
• Apollo Flame, in both the second and third games. 2500 HP to start, and that number just keeps climbing. Has a shield that regenerates very quickly and very often, and also has an unavoidable attack that does huge damage, cracks the floor and it's hard to knock him out of it. Also, his weakness (Water cards) doesn't have a lot of heavily-damaging moves - the best ones out there are secret cards, and unless you're really, REALLY lucky, you won't find them.

Mega Man Star Force 3

• In terms of storyline bosses, Acid Ace in 3. He has a huge repertoire of moves, with something to break any Noise, and he doesn't follow a clear pattern with them. Then there's the matter of his R form, which is fought directly after Dread Joker R without a chance for you to heal.