[[quoteright:260:[[VideoGame/MegaMan2 http://static.tvtropes.org/pmwiki/pub/images/airman_taosenai_nekokan.jpg]]]]
[[caption-width-right:260:[[MemeticMutation You'll wish you just had to fight Air Man after dealing with these guys.]]]]

''Mega Man'' stands as a shining example of classic NintendoHard. These guys are the reason why. It doesn't matter if you've got the [[GoodBadBugs Time Barrage glitch]] or a [[VideoGame/MegaManBattleNetwork folder full]] of [[LimitBreak Program advances]], these mechanized murder Masters are coming for you.

Please keep in mind that if there's an easy method to take out a boss, they're not this trope. Remember as well that WeAreNotGameFaqs; your example shouldn't read, "Unless you do..." or "But if you have..." If there is a trick to defeating the boss, it's probably not an example in the first place. This being ''Mega Man'', every boss has a weapon that they're weak to[[note]]with only a handful of exceptions, many of which are on this page[[/note]]. If that weapon turns out to be impossibly frustrating to use, that boss probably belongs here.

BonusBoss is now banned from being ThatOneBoss. It's optional and you know it's overpowered; nothing prevents you from not fighting it.



[[folder: ''Mega Man'' (Classic series)]]

* Fire Man, mainly because his fire pillar attack is very powerful and you have to have ''perfect'' timing to jump over it. He also frequently uses this move as well as his regular Fire Storm like there's no tomorrow, so even having the Ice Slasher isn't going to guarantee you victory.
* Ice Man and Elec Man are also worth a mention, because they do insane amounts of damage to you, capable of taking you down in three hits, and while you can do the same to them with the weapons they are weak against (and in Elec Man's case, your special weapon directly nullifies his shot), this doesn't guarantee victory against Ice Man; instead, it becomes [[RushBoss a short but frantic battle of who can kill the other faster]], and if you don't have the weapon he is weak against, [[ThisIsGonnaSuck oh boy are you in for a ride]] you have to make very precise jumps between his constant shots to avoid getting hit while also trying to aim to the right height to hit him. Did we mention his is the game's {{Slippy Slidey Ice World}}? So you'll also have to account for inertia when maneuvering around his shots. Have fun.
* The Yellow Devil from Wily Stage 1. As lamented in [[http://www.youtube.com/watch?v=hN-YHyDrCdc& this song]], many gamers have lost a good chunk of their childhood trying to get past this shining example of NintendoHard. Unless they cheated.
** The Yellow Devil's difficulty stems from his attack pattern; he splits apart and flies across the room one piece at a time, and you have to have crazy good reflexes or have to have memorized his pattern to dodge him without getting hit. Once he's fully formed, his eye opens and fires a fast-moving projectile at you, then it closes and he starts flying across the room again. You only get a couple of seconds before the eye closes, and if you're trying to kill him with the Buster, the eye sometimes opens too high to hit. Not only that, but he takes forever and a day to die.
** 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.
** The key to surviving this fight is to ''memorize the entire splitting pattern'', since it doesn't change at all. Fully knowing when you should jump and when you should stay on the ground gives you a significant advantage. However, [[GoddamnedBoss the boss is still annoying to deal with]] because of the short windows of vulnerability.

* If you don't have his weaknesses, then Wood Man is a hassle to defeat. He hits hard, and he is also one of the more durable Robot Masters. His hardest attack to dodge is his Leaf Shield, which requires a well-timed jump to dodge. You also have to worry about his swirling leaves, which require good evasive maneuvers to get through. And what's worse is that he advances towards you after each attack, forcing you to run under him (good luck not getting hit by him as you do this) to the other side while dodging his leaves as they descend. Yeah...don't fight Wood Man first.
* Air Man is an interesting example. Due to [[EarWorm a certain song]], he has been elevated to MemeticBadass status, despite being only moderately difficult (indeed, ''Magazine/NintendoPower'' actually started with Air Man on their guide). The context of the song lost in translation was that it was about a player who never played games trying out ''Rockman 2''. Modern Western fans are left scratching their heads, [[MemeticMutation but the meme just stuck around]]. [[note]]Another thing that gets lost is that not only is the singer a newcomer to the series playing on the Japanese version, which has only one difficulty setting, he also gets stuck in a loop. He gets stuck at the disappearing blocks in Heat Man's stage, so he looks up what could help and finds that the item you get after Air Man is a glider with which you can skip it. He goes to Air Man, but cannot defeat him. He looks up Air Man's weakness and finds it is the leaf Shield of Wood Man, but cannot defeat Wood Man either. Wood Man's weakness is the flamethrower of Heat Man... but he's actually vulnerable to several other weapons too.[[/note]]
** The main problem with Air Man is that he can [[RandomNumberGod sometimes]] throw out his tornadoes in patterns that require extremely precise jumps to dodge. To a normal player, this isn't so bad, as it's not too difficult to damage Air Man faster than he damages you, [[LuckBasedMission but trying to do a]] NoDamageRun...
* Quick Man, right after his own [[ThatOneLevel hair-pulling level]]. He is incredibly fast, and takes out almost 4 units of your life bar via contact. While Flash Man's Time Stopper can take half his life in one shot, the player will probably need it to get past the daunting laser barrage right before his door.
* The Mecha Dragon in the first Wily Fortress stage. Someone even wrote a blog entry in which this boss fight was compared with a major real-life hangup. Made harder in ''Anniversary Collection'', which removed [[GoodBadBugs 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 five seconds or so. It's one of two bosses in the Wily Castle that only has one way to damage it, the Crash Bomber. And the kicker? You only have seven uses of the weapon maximum. Five to actually destroy the turrets, and both of your remaining shots to break barriers blocking the others. To make matters worse, there are plenty of other doors you can bomb to [[ShmuckBait 'make your life easier']]. This is a cruel beginner's trap, as there is no way to win if you use just one bomb incorrectly. If you don't make clever use of Items and/or accidentally miss a shot, then [[UnwinnableByDesign 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 in the pre-boss hallway or just game over entirely and restart the stage. There's a reason why practically every ''VideoGame/MegaMan2'' ROM hack out there, even the obscenely hard ones, generally make this boss ''easier''.
** The only mercy you're given is that the barriers you destroy don't respawn. Unless you game over. Small mercy, because, as previously mentioned, now you need to grind up all your crash bomb ammo from the Demonic Spiders of this game.
** Or you can leave the two weapon energy containers at the beginning of the level, destroy the barriers, die, and then come back to the start of the level and refill the Crash Bomb.
* Wily Machine 2, the boss following the BossRush, has a fairly easy first form, which is fair and balanced. The second form throws all that out the window and has attacks that are completely unavoidable. That's right this boss is literately impossible to defeat without taking damage outside of a bug exploit. The worst part is, it looks like the fight should be an easy one, but it's due to some [[HitboxDissonance very wonky hit detection]], you'll be taking damage from things that clearly ''miss'' you. Fortunately for the player's sanity, the actual final boss is [[AntiClimaxBoss significantly easier.]]

* 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 even ''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!
** Oh, and since it's ''VideoGame/MegaMan3'', you now have to try and figure out which weapons the ''VideoGames/MegaMan2'' robots are weak against all over again. Almost none of them are intuitive, either. Even when you ''do'' figure out their weakness, they aren't as effective as their weakness was in ''VideoGame/MegaMan2'' (nothing can break through the Leaf Shield, for example).
* Doc Wood Man, 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 [[MortonsFork smacks you into the leaves coming from above]]).
* Doc Heat Man, who, just like Shadow Man, is vulnerable to the Top Spin, and it's very easy to use up the weapon energy for it without defeating Heat Man if you're not lucky. Luckily, Top Spin isn't the only good option to fight him.
* Doc Air Man is weak against Magnet Missile and Spark Shock, two weapons that are not quite effective at actually hitting him. If you die against him, you have to start the entire stage over, as opposed to getting dropped in the previous room like the other robots.
* [[ConfusionFu The Doc Robot mimicking Quick Man.]] Remember how in ''2'', Quick Man was a FragileSpeedster and ''still'' tricky to beat? [[LightningBruiser Remove the fragility and increase his size]] [[OhCrap and you have this boss.]] It says a lot when the most basic strategy is to ''deliberately try to get hit'' by his boomerangs, which hurt far less than [[CollisionDamage colliding with him]], which is a near-inevitability.
* Flash Man's simplistic pattern in ''2'' made him a pushover. However, the same can't be said for Doc Flash, as small changes made this pattern an actual challenge. He's taller than Flash Man, so it's difficult to jump over him without getting hit. He uses Time Stopper more often and the SpreadShot that he fires during Time Stopper covers a much larger radius than Flash Man's. And if you're not careful, pressing the Shot button while getting hit by the Spread Shot will ''cancel your MercyInvincibility and you'll get hit again''! Oh, and like the other Doc Robots, he hits harder and has more durability. Luckily, Doc Flash doesn't jump after getting hit like Flash Man did, which would have made this already difficult battle even more challenging.
* Shadow Man. He is insanely fast, and his attacks are very hard to dodge. On top of this, the only weapon that can hit Shadow Man effectively, the [[ScrappyWeapon Top Spin]], has to be used at very close range, and its weapon reserve energy drops like a stone when you are using it while in direct contact with Shadow Man. What tends to happen is that if you try attacking directly with Top Spin, ''all'' of its weapon power can get drained when you land your first hit. Then Shadow Man still has 75% health and you have no Top Spin power left. Good luck hitting him with the Arm Cannon, and even if you know his pattern, he is still very difficult to beat.
* Dr. Wily has a second incarnation of the infamous Yellow Devil, the Yellow Devil MK-II, waiting for you in the second stage of his castle. This Devil boss is, however, considerably easier, since its normal attack isn't as fast as its predecessor (and the blocks come at you closer to one-at-a-time intervals), and you have sliding and E-tanks. Good luck getting through its "bounce across the room in pieces" attack without getting hit, though.
** If you're performing a run of the game without using any E-Tanks, or worse, without taking any damage, then this Yellow Devil is harder than the one in ''VideoGame/MegaMan1'' because of the above bouncing attack.

* Dive Man, mainly because he's quick and aggressive, and the one weapon that does any real damage to him is the [[ScrappyWeapon Skull Barrier]], which is so small that colliding into him with it pretty much means you're going to take ''huge'' damage in the process. It doesn't help that Skull Barrier disappears if ''any'' projectile touches it. Dive Man's weapon is also a homing missile. Since you can only afford one or two mistakes using Skull Barrier, you basically can't do anything until you know you have a clean shot at Dive Man. [[ViolationOfCommonSense You essentially have to be close to an enemy that wants to ram into you]].
* Ring Man, mostly because of his massive CollisionDamage, dealing eight units of damage if he collides into you. He also has an erratic and unpredictable AI pattern, and if you think you can stay on the ground to attack him, he'll immediately counterattack you.
* The second phase of Wily Machine Number 4 is absolutely brutal if you don't realize you can [[spoiler:pre-detonate the Drill Bomb and explode it to hit Wily's weak spot: any other weapon (save for the Mega Buster) does little to [[NoSell no damage]], and if you don't detonate the drill just before it hits the weak spot, it'll just bounce off]]. He fires a constant barrage of huge fireballs bigger than Mega Man with no discernible 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.

* Gravity Man. The fight against him is purely disorienting, and the switch in controls can often take your slide out of the equation for the most part. Hitting him with anything can be difficult because of how tiny a window you have to do so; this, combined with the fact that his shots tend to be uncannily accurate, leads to much aggravation. He also has a nasty tendency of shooting your Star Crash to cancel it out right before switching the gravity, therefore removing your opportunity to hit him ''and'' wasting the weapon's energy.
* Dark Man 1 simply moves slowly and stops to shoot often and upon taking damage. However, upon taking a certain amount of damage, he will move faster, and become more difficult to avoid. His weakness, the Water Wave, only has 14 uses, so it is likely that dying to him will mean players will end up fighting him with little or no uses of it left.
* Dark Man 3 fires three rings that immobilize Mega Man completely, allowing him to hit him easily (which will pretty much always happen). They're difficult to dodge at a close range as well. His major weakness, Beat, is a weapon that can only be found by collecting all the plates that spell "MEGAMANV" in the Robot Master stages (the G in particular is for GuideDangIt, being hidden behind a shootable wall that looks like any other wall in the area) and thus some players may not have. In addition, the boss after Dark Man 3 is also weak to Beat, and the stage containing it is short with absolutely no way to refill weapon energy, so players that ''do'' have Beat will want to save it for him.

* The dinosaur robot boss Mechazaurus has a [[GoForTheEye weak spot]] the size of a pinhead that can only be reached by riding the flying platforms that emerge from its chest, and said weak spot is picky about what counts as a hit and what doesn't. It also periodically spits fire blasts with deadly precision, which is highly likely to hit you while trying to ride the platforms up, and if a flame hits the floor, it lingers there for a second. Its weakness (the Yamato Spear) is fairly limited in uses, so it's possible to run out of it because they didn't count as hits.
** [[spoiler:[[PuzzleBoss You can, however]], switch to the Power Adapter, stand in the blind spot of its fire, and use the Power Adapter's [[ChargedAttack charge shots]] to [[HoistByHisOwnPetard deflect the platforms back at it]] to damage it with no risk to yourself, effectively making it a [[ZeroEffortBoss Zero-Effort Boss]].]]

* Slash Man, who's fast, strong, and can immobilize you with a red adhesive-like substance. It doesn't help that it's also really hard to hit him with his weakness weapon because he's always jumping around the room.
** To elaborate, Slash Man has three different attack patterns. One where you can freely shoot him because he keeps following you and trying to slash you, one where he will make a big jump directly towards your position that can be dodged with good use of the slide...or his favorite pattern, where he goes to the ceiling, starts dropping 5 blobs of goop that immobilize you and then he can randomly choose to wall dash at you or go back to one of his starting patterns. The blobs don't have any pattern, so you must depend on your reflexes to dodge them, and if you get hit by one, you have to button mash fast enough to get out of that predicament, and if you're unlucky enough, you will only get hit by another blob. That or Slash Man uses his wall dash and hits you for massive damage. The kicker? His weakness (Freeze Cracker or Scorch Wheel) makes him repeat the third pattern over and over. Is there any wonder Slash Man is seen as TheScrappy of the classic series by some?
* The first duel with Bass is ''very rough''. You fight on a irregular, cramped arena and Bass simply doesn't stop shooting and jumping and his charged buster is nigh impossible to jump over if you're in the wrong position. Sure, you can crush him with the Super Adapter or Noise Crush, but facing him using the old Buster weapon is a nightmare.
* The final fight with Bass, when he combines with Treble, can be extremely tough if you don't have the Super Adapter. If you ''do'' have it, the fight is still tough, [[BestBossEver but a lot more awesome.]]
* The Wily Capsule 7 also fits here. He is definitely overly hard by the standards of final bosses for the ''Mega Man'' series. His main attack is shooting four elementally charged orbs in your direction, then [[{{Roboteching}} they stop in mid-flight to adjust their path twice]]. The ice sphere hurts less, but freeze Mega Man in place, while the fire sphere is as powerful as Turbo Man's Scorch Wheel. To properly avoid the the orbs requires a rhythmic jump-dance based upon the sound of the orbs changing direction, but it can take time for one to realize this, as the frustration can make it hard to adapt.\\
His weakness, the Wild Coil, is (as per the tradition) difficult to hit him with. Fortunately, he's at least damaged by some other, easier to hit with weapons, such as Freeze Cracker. WordOfGod says that even the developers found this one impossible without E-Tank usage. Even has some LampshadeHanging, in which Mega Man attempts to kill Dr. Wily following the battle. [[CrowningMusicOfAwesome The one redeeming thing about this boss]] is the [[https://www.youtube.com/watch?v=BOXn5BrHOgM fittingly frantic, overpowering, and badass music]].
** This battle is ''so'' bad that the creators actually used it again as the final battle in ''VideoGame/MegaMan8'' 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 ThatOneBoss.
** You know the boss fight is ridiculous when a common bit of advice for fighting him is "Just get hit by the yellow orbs. They hurt less."
*** Luckily, there's a way to drop the battle's difficulty just a little bit: Once you hit him with your weapon of choice, you need to pause ''immediatly afterwards'' and choose the Thunder Bolt from the menu, un-pause, and hit him with it. This will electrocute Wily and make him unleash the thunder spheres he uses against you when he succeeds in freezing you. This time around, however, you're not, so you can dodge the attack with ease. It'll make the fight longer but at least you'll worry a little bit less about the main way he attacks you.
*** Providing you have really good timing, you can use Rush Coil, ''of all things'', to evade the four-sphere attack. Although it's less about actually dodging them and more like misguiding them while you jump.

* 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 ThatOneLevel, 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. The biggest reason this counts, though, is because it's a GuideDangIt moment if you hold the up direction while kicking the ball, it goes at an upward angle instead of forward. This boss is a whole lot less annoying if you know this trick, but of course that doesn't mean the game ever tells you this.

* The Paozo elephants from Concrete Man's stage. What makes it worse is the fact they're ''only mini-bosses''. These guys are also found in the downloadable Special Stage featuring [[spoiler:Fake Man, the impostor police robot who arrested Dr. Light]] and Endless Attack.
* Concrete Man hits very hard, the Laser Trident doesn't do much damage to him, and he has an unavoidable, heavy-damage charge attack if you're stuck in concrete. While the Laser Trident can pierce through the block of his weapon, it don't work if you're trapped in it -- and they travel diagonally from the air and are ''very fast''. He's so bad that he can even screw up the BossRush.
* Tornado Man, mainly because his attack is ''very'' difficult to dodge if you're not fast enough to avoid and his weakness weapon is a ground-based attack and he spends most of the time flying in the air.
* What's worse than one Devil? ''Two of them at the same time''. Both the yellow and green devils send 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 painful. Fortunately, the pause-glitch works on it.
* Dr. Wily in this game rivals his ''VideoGame/MegaMan7'' incarnation. A three-form fight with ''no breaks'', and the first has a very unorthodox way of dealing damage. It doesn't help that it's pretty hard to hit Wily Capsule with Plug Balls, as the ball will go straight down when in midair and he often spawns in midair, meaning you have to be on top of him to hit him.

* Strike Man is one boss who both inverts this and plays this straight depending on the circumstances. He's the easiest Robot Master to beat with his weakness weapon [[GameBreaker the Triple Blade]], but the hardest to beat if you don't. His Rebound Strikers are very fast and he can have multiples of them at once. He's also the boss of a level that has not one, but ''two'' annoying mid-boss fights. Better hope you have his weakness weapon, or a lot of E-Tanks, because if you don't...
* Blade Man is like a powered-up Shadow Man from ''VideoGame/MegaMan3''. He's 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 shockwave from the explosion has to hit Blade Man before he jumps to the ceiling or another wall.
* The ''Block Devil''. Imagine, if you will, an unholy union between the Pico Pico Master (2nd fortress boss from ''2'') and the Devils' penchant for splitting and reuniting in definite patterns, throwing in a weak point that stays on screen for only about 1/3 of the battle and ''a bottomless pit'' that becomes a KaizoTrap if you happen to defeat the boss standing on/over a purple block. Its weakness is one of the most awkward weapons in the series, too!
* From the first bonus stage, Enker. In order to compensate having a much larger arena than he did in the Game Boy titles, he moves significantly faster, and his pattern has been altered to occasionally have him jump or dash just to the middle of the room, then change his movement, making him harder to dodge. Oh, and he's still invincible when he's not charging up his Mirror Buster and still retains that whole immunity to everything except the Mega Buster thing [[spoiler:unless you beat Ballade in the third bonus stage]].

* 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). Mega Man has an easier time because he can slide under Dynamo Man's attacks and use charged shots to take out the recharger faster, but Bass has his work cut out for him.
* Even worse than Dynamo Man is Burner Man, who resides at the end of ThatOneLevel, 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 PuzzleBoss, having to use the Wall to push him into the spikes on either side of his arena. Thing is, Ice Wall can be only used when he is on the ground; 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. And unlike Dynamo Man, he's a real challenge for both Mega Man ''and'' Bass.
* If you play as Mega Man instead of Bass, a boss that's a relative pushover for Bass becomes a nightmare for Mega Man: Tengu Man. Tengu Man flies around constantly and in confusing patterns, generally out of the reach of Mega Man's shots (Bass could simply angle his shots upward), and his flight from offscreen is difficult to dodge as Mega Man (Bass could simply double-jump Tengu Man's flight charge).
* King Plane 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.

* In ''Mega Man 1'', Cut Man was pretty easy to take down with the default Mega Buster, and a complete joke if you had the Super Arm. In ''this'' game, he moves far faster, his Rolling Cutters are even faster still and far more damaging than they were on the NES, and Cut Man's weakness (the Fire Storm) isn't anywhere near as effective as his previous weakness to the Super Arm.

* Crash Man[[note]]Or "Clash Man" as the game calls him[[/note]] stands out in what is otherwise a ludicrously easy game, as he's the only Robot Master to actually be ''harder'' than on the NES. His weakness is still to the Air Shooter, but he takes much less damage and will only be hit by one of the three tornadoes from each shot (all three could hit him in the NES version), meaning even if you hit him with every shot, he'll still have about a quarter of his health left. On top of that, you fight him in a much smaller arena than you did on the NES, making it much easier to pick up SplashDamage from his bombs.
* Living up to his MemeticBadass legacy, whilst generally fairly easy to defeat, Air Man in this game has a tornado pattern that is quite literately impossible to dodge. And he has a 1/4 chance of using it every time he fires. [[LuckBasedMission Have fun no-damage runners!]]
* This game's Wily Machine can come as quite a shock after the easy time that the rest of the game gives you. The biggest issue is that all three phases have attacks that are extremely difficult to avoid, something made worse by the game's HitboxDissonance. In addition, the only weapon that can do decent damage to Wily is the Sakugarne...which also ''damages Mega Man'', so much so that it's a lot safer to just stick with the Mega Buster and deal with Wily's attacks.

* Punk certainly lives up to his Mega Man Killer title. He deals a serious amount of damage just like Elec Man and Ice Man. He throws very fast-traveling projectiles while jumping, and then he curls up and cannonballs himself to the other side of the room at a breakneck pace, and the height he cannonballs at is done at a varying height, which means you have to slide under or jump over him accordingly. And he ''only takes damage from the Mega Buster and nothing else''. Good luck!

* Bright Man is easily the cheapest Robot Master in the game. Why? Well, remember how in ''Mega Man 4'', he would only use the Flash Stopper when his health was at a certain point? Yeah, that quirk's gone now he uses it whenever he wants and will seemingly ''always'' abuse it to jump into you while you're completely helpless to avoid it. Put simply, if you walk into his fight with anything less than full health and/or E Tanks, he's already won.

* Uranus is easily the hardest of the game's Stardroid bosses. Not only do his attacks cause ''major'' damage, he has a OneHitKill move that he frequently spams you with, and only Pluto's weapon, the Break Dash, is capable of causing him more than a single damage point (even a fully-charged Mega Arm hit does just one point of damage).
* The final boss, Sunstar, has ''no weaknesses'' and three forms, all of which can do major damage to you.

* If you're playing as a "Boss Character" Robot Master, when you have to fight the Master whose weapon is strong against you, ''good luck''. Your attacks will barely scratch them, and they can inflict a ton of damage on you in turn.
** 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.
** ''Any bosses'' when playing as Oil Man, but ''especially'' Fire Man. He can turn your already-pathetic attacks against you ''hard'' by [[IncendiaryExponent lighting them on fire.]]
* CWU-01P, especially when playing as [[JokeCharacter Rock/Mega]]. His main way of hurting you is CollisionDamage. Sounds easy, right? WRONG! At least on the aptly-named Hard Mode, he's damned fast. And as the aforementioned JokeCharacter, 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 [[FrickinLaserBeams frickin' laser beam!]]

!!''Game Gear Mega Man''
* Napalm Man, who went from being one of the easiest bosses in ''5'', to one of the hardest here, all thanks to a change in AI that makes him very aggressive, and no longer follows a predictable attack pattern what-so-ever. On top of the AI change, everything he fires at you now explodes, rather appropriately, which makes even his first barrage of attacks pretty tough to dodge on such a small screen.

* Vega (Claw). He only uses melee attacks, but he's [[LightningBruiser very fast and does a large amount of damage]], and his weakness is a melee attack. He also has ThatOneAttack where he leaps onto the railing and tries to slash down on you, and is very hard to evade if he performs it in the middle of the arena (hint: slide when he is halfway down to feint him). In fact, the move you ''want'' him to use is his Limit Break, which isn't too difficult to evade and leaves him open in the center after it ends.


[[folder: ''Mega Man X'' series]]
* Boomer Kuwanger is an absolute monster without his weakness weapon, mainly because he can easily teleport through your other weapons and counter you with his [[ThatOneAttack Dead Drop]], and his dashing capabilities far exceed yours, which means that running from him while dodging his Boomerang Cutter that can hit you while you're wall climbing make for quite a frustrating time. Even players who prefer to mainly use the X-Buster for the majority of their playthroughs will make a ''big'' exception for this guy, which makes perfect sense considering he's like the Quick Man of this game.
* Launch Octopus is a LightningBruiser who relies on MacrossMissileMassacre if you fight him without dashing. He can stop firing and start his whirlpool to LifeDrain attack very quickly, and the only warning you get is how fast his jump is. Newer players may select Launch Octopus first due to his icon being the default on the Maverick selection screen, only to be blown away due to not having obtained the dash boots from Chill Penguin's stage.
* Armored Armadillo 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.
** If you're playing as Vile in ''MHX'', you ''will not'' have Peace Out Roller (the same thing as Electric Spark, except it's lobbed instead of shot) for when you fight him, because its weapon type is locked until you beat him! That's right, you unlock a boss's weakness by defeating that boss. To make up for this, he's also weak to the fist weapons, which you ''do'' get from Spark Mandrill; however, they don't remove his armor.
* Sting Chameleon. One of the few bosses in the game widely considered to be a total death wish for new players, and still a pain for even veterans. The very annoying part about his fight is when he clings to the ceiling to rain the spikes in his room down on you, which fall quite fast, aren't all that easy to dodge, and their damage adds up eventually. On top of that, thanks to his ability to disappear and reappear at will to attack as well as to dodge ''your'' attacks, it turns his battle into a very long, hit-and-run war of attrition. His iron tongue attack is ''lightning'' quick and does good damage, and he can take plenty of punishment as well. If you slip up even a bit in this fight, you ''will'' pay for it.
* The Bospider, 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 her before she regains her invincibility. And then she TurnsRed...Good luck hitting it with its weakness, too. It's not even good against the mini-spiders, since it'll only hit one and the firing rate isn't fast enough to shoot at the one behind it.
* However, the most difficult boss in the game by far is Wolf Sigma. The first time you fight him, you will be surprised by the sheer increase in difficulty from his previous forms that can be easily locked into exploitable patterns. Only two weapons can hit Wolf-Sigma's head, and both are un-wieldly. A fully charged buster shot, a 5-10 second charge, does 1 damage. The Rolling Shield, the most annoying weapon to use in the game thanks to an inability to fire straight, does two. However, this is just how you damage him. His attacks do anywhere from one 'weak' hit of 5 damage, or 10-14 damage out of your life bar, a 4HKO at most. This is only aggravated by what those attacks are. This boss has two hands and each can do two attacks. They can shoot lightning, which is telegraphed, covers an entire column of the screen, and will be spammed. The hands also swipe at you, which is your one true opportunity to get on them and ride them up to Sigma's head. Unfortunately, you won't have much time. As soon as the hand gets back to its original position before the swipe, it will shoot lightning. There is one other opportunity to get on the hands: wall jumping up the sides and praying that his hands are both out of position and not firing. Sigma's head also has two attacks. It telegraphs when, but not which attack it will use. It can fire electric sparks which take an almost perfectly timed dash to dodge, if you are not in the corner where it starts. It also can breath an impassable stream of fire which can start in the mid-right or mid-left of the room. Since you have no idea which attack Sigma will use, nor where it starts, you have a 1/4th chance of getting hit without a chance to dodge. The lightning from the hands attacks separately, and loves to trap you between fire and lighting. This is the worst fight in the game, bar none. And third in annoyance to the Yellow Devil and Boobeam Trap in the entire series.

* Magna Centipede isn't just difficult, but an outright LuckBasedMission if you don't have his weakness, or at the very a least a near-full set of upgrades. His favorite trick is to use an attack which can only be avoided by spamming dashes and will gradually cripple X's combat abilities for the duration of the battle, eventually leaving X with no charge shot, a slow firing rate and limited jumping abilities. After that, he'll bombard you non-stop with ninja throwing stars until you die. While having his weakness does make things a ''lot'' easier by taking out his disabling attack, that still leaves you with a constant stream of throwing stars, and his habit of rapidly teleporting and bouncing around the room makes it difficult to hit him with follow-up attacks.
* 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 they HURT. 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.
** Zero's AI is easily predicted/manipulated and all of his attacks are avoidable. All of which means absolutely nothing, as Zero is just too damn fast. Slipping up AT ALL will have you eating his attacks as he grinds your face into the floor.

* Volt Catfish is an absolute nightmare of epic proportions. His attacks are inanely hard to dodge, as you'll be dashing for your life the entire fight, with not even a second for a breather. He's also incredibly unpredictable, as even with all your dashing prowess he'll manage to somehow use the move that hits you at that exact spot anyway. The worst part is his half-hp move, which renders him invulnerable for a good 15 or so seconds, all the while you have to dodge electric sparks going everywhere and at the end he does an extremely damaging headbutt with no warning whatsoever. ''And he proceeds to spam this attack for the rest of the fight.'' However, by using his weakness (Tornado Fang, one of the easiest weapons to get with an armorless weaponless Megaman) his threat is reduced several levels. While having such a big weakness would make him not qualify for this list, the sheer unbalance between fighting him with it and without it should be noted.
* If you defeat Bit and Byte with their weakness, then you'll be able to skip the battle against Godkarmachine O Inary and fight the Press Disposer. If you don't, you're in trouble at the end of Doppler Stage 1. The Godkarmachine O Inary is a formidable opponent on the SNES version who can do major damage to you if you're not quick enough to dodge his attacks, but on the Playstation remake which is also on the Mega Man X collection disk, this boss becomes a real ''nightmare''. Its attack, defense, and speed are ''much'' higher than they should be, and even with the [[SuperMode Gold Armor]] found in the same level, this boss might require multiple sub-tanks to defeat if you're not careful, as its damage output easily rivals the FinalBoss Sigma's.
* Sigma and Kaiser Sigma. Sigma's swapped out his Z-Saber and WolverineClaws for a ComicBook/CaptainAmerica-esque shield, which [[LuckilyMyShieldWillProtectMe defends him from all attacks as long as it's bared]]. His main attack consists of spraying fireballs all over the place, and while these have obvious patterns they are blazingly fast, adding to the frustration. At 50% health he will start spamming his shield attack, that while also predictable is extremely fast. When you defeat him, Kaiser Sigma appears. His battle body is so big he fills one third of the screen and his weak spot is the size of a pin. His weakness? Oh wait, he doesn't have any weakness and he's only damaged by charged Buster shots in the game with arguably the worst Buster upgrade in the X series so you're stuck with level 2 and level 3 charged shots. He has 2 patterns, one when you're facing his back and one when you're in front of him. The first makes him shoot several tracking missiles that hit extremely hard. The second makes him charge a laser that tracks you and continuously damages and stuns you when you get hit by it. All the while he's spawning tracking bombs. And to add insult to injury, the first time you try to hit his obvious weak spot, you will find out that you need [[HitboxDissonance to aim for his battle body propellers instead of the head]].

* Isaz and Sowilo, the tank boss at the end of the second fortress stage; it has two faces that must be destroyed to be defeated, and both require the usage of both characters to hit. Sounds awesome, right? '''WRONG.''' The tank takes up a ''good'' portion of the screen, and spends ''much'' of the battle restricting your movement space on the very left edge of the screen on top of the moving platform, and can only be pushed back by using Zero's sabre or if enough time passes. The upper face shoots a set of three energy balls that are almost impossible to dodge, while the lower face shoots a missile upwards that then comes down on your position. Between this, and the fact that the projectiles actually ''move with the boss'' when Zero pushes him back, and you have one of the more poorly coded bosses since the Buebeam Trap from ''VideoGame/MegaMan2'' and Doc Robot's Wood Man form from ''VideoGame/MegaMan3''.

* Magma Dragoon, considering he has both the fire-based [[Videogame/StreetFighter Hadoken (Fireball) and Shoryuken (Dragon Punch)]] and loves to constantly use 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 UpToEleven with Zero, who has to slash him at close-range, unlike X who can easily fight him from a decent distance away.
** As a nod to just ''how'' tough he is, the game will allow you to enter this battle with ''[[PoweredArmor Ride Armor]]''. Which you ''will'' lose to the aforementioned stream of fire attack unless you enter the lava behind him quickly, and the Ride Armor isn't exactly good in the speed department. Still, you can knock off a good portion of Dragoon's health before you inevitably have to finish the job on foot.
* Storm Owl, a flying boss with variety of dangerous attacks. His swooping move is hard to predict and avoid, and will deal high damage to you should it connects. His feather shots cover a wide area, and he can summon wind orbs which float onto a position each (covering parts of the area) and block your shots, then fly towards your position. There's also his DesperationAttack where he spams wind orbs to 4 directions; you have to constantly move to stay on the safe spot (including upwards to the the top platform). Oh, and he puts a wind barrier that blocks your further attacks whenever he gets hit too much. He's easy with his weakness weapon (even the hard-to-use Rakuhouha) but he's daunting without it.
* Sigma's an exhausting grudge match, with ''three'' forms, the last consisting of two separate bosses that switch in and out of the fight and do NOT share health, and no breaks in between. The first form goes down easily enough, but the second delights in chasing you around with his SinisterScythe 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 a wind attack that can knock you into some (non-lethal but very painful) 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.''
** As if to prove how nasty ''X4''[='=]s Sigma is, the game actually ''gives you an energy capsule between the second and third forms.'' It's the ''only'' time a Mega Man final boss is so generous.

* The Skiver/Spiral Pegasus, which is basically a tougher version of Storm Eagle; he boasts the same sort of attacks, but all vastly more difficult, coming from all directions at high speeds. 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 Dark Hold, which doesn't last long enough to punch off a decent portion of his health.
** To make up for the fact that he doesn't have similar pushing abilities as Storm Eagle, any contact with him will push X or Zero ''a lot farther''. Did you collide into him next to a pit? You're probably going into that pit.
* Squid Adler. His strategy is basically [[BulletHell filling the screen with lightning projectiles]]. Also if his health is depleted by 1/3, he'll electrify the floor (temporarily), forcing you to take the walls and the floating blocks he oh-so-kindly summons for you (which can also disappear without warning). Worse, he might sometimes summon ''electrified'' blocks instead, and his DesperationAttack is him firing a wide spread of lightning at once. The weapons he's weak to are hard to use; X's Goo Shaver will go downward diagonally if fired in midair (and he flies a lot), while Zero's F-Splasher will require him to ''airdash towards him'' (which will damage Zero as well if you're not careful).
* Shadow Devil in the first virus stage; it 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. The [[BoringButPractical C-Sword]] can be used as an alternative, but makes matters no less difficult.
** Shadow Devil also leaves a green outline behind when it splits...that does a LUDICROUS amount of collision damage to you.
* Gamma Sigma may have an unfinished battle body but he's no pushover. He likes to alternate between invulnerability and vulnerability periods while continuously shooting electric balls and trying to crush you with his hands. To top it off, he has 2 extremely hard to avoid attacks. One makes him spawn an energy cube that follows you at light speed and makes humongous ammounts of damage even against armored X and takes about one third of the screen. The energy cube will fully acquire form after a few seconds of chasing you and then it will still follow you so you need to have god-like reflexes to avoid it. The other one makes one of his hands shoot lightning from above and will also track you to hit for humongous damage, so you need to take refuge right under his lightning attack blind spot. The hand will keep moving so you need to follow along slowly.

* Infinity Mijinion, whose main gimmick is cloning an infinite amount of himself. His clones have the uncanny ability to get in your way a whole bunch until you forget which one's the real one. The clones also releases slow-moving homing blobs of goo which further add to the difficulty. Even getting to him is a huge problem because the entire stage is spent fighting Illumina, which is no walk in the park either. Heck, this is a case in which using the boss' weakness probably makes the battle ''harder''. Hitting him with the uncharged Guard Shell is difficult, if only because it only works against one of his attacks (which is unpredictable to use, 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 UpToEleven 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.
* The Nightmare Mother is already a rather hard boss on Normal mode, but on Xtreme, it becomes one of the most difficult in the game. 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. When they do stop to attack, welcome to BulletHell. Each eye can release one of four attacks:
** Shockwave-producing Blue Orbs: This is the easiest attack to dodge, as the projectiles are slow and predictable. However, it's easy for them to sneak up on you when you are dodging one of the other three attacks.
** Fireball Rain: The eye will unload fireballs into the air, where they will fall upon you like a fountain. The pattern isn't random, but it is unforgivably fast, and you have little room to dodge. This becomes a much worse problem when you have another attack to dodge.
** Flaming Floor: Exactly what it sounds like. The floor is covered in fire, forcing you to take to the walls. Again, this is only to cut off your dodge room for whatever other attack may be coming your way.
** Lightning Orbs: The worst attack. The orbs will hover back and forth halfway from the ceiling and fire lightning at random. This is nasty because there's no timing to them, and it's not telegraphed. The only way to know if the orb is about to fire is if you've already been hit by it.
* Gate is quite unpredictable, and has total invulnerability to all of attacks save for [[TennisBoss his energy sphere attack.]] At that, he spends most of the time flying into you rather than using it. His attacks are extremely difficult to predict and retaliate with, since they need to be level with him, and then hit him in the face as they break from damage. [[MalevolentArchitecture Try doing all that over a bottomless pit where the only footing you'll ever get is a handful of small ledges.]] The "gates" that he spawns that you're supposed to damage him with don't make the battle any easier. One follows you around the room, another fires at you, yet another pulls you toward it, and they explode in six different directions, meaning you're likely going to be hit in one of them. When he TurnsRed, he gains an attack that destroys those tiny little ledges that you're supposed to land on. Sub-Tanks are more or less a waste, since the usual cause of death here will be falling to your death due to Gate or his attacks flying into you. At least the game grants a tiny bit of mercy by giving you bottomless pit invincibility when you defeat him.

* Snipe Anteator. On paper, his weakness was the Moving Wheel. In the game, hitting him with his weakness is difficult. Even if you could, it actually did less damage than a fully charged X-Buster. However, X is not available from start. On top of that, he doesn't have a stun animation, meaning that he can counter your attacks ''as they hit him''.
* Then there is Flame Hyenard. You had to damage a mech traveling over hot lava so you could get to him. This is easier said than done since [[CameraScrew the camera can screw you ove]]r. Then you fight Flame Hyenard. He splits himself into clones that shout [[MostAnnoyingSound "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 ScrappyLevel 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 contact while slashing him.

* Ravemanta, the miniboss in Avalanche Yeti's stage. It takes a long time to kill, and appears twice in the stage. The first time, it's a fairly tame if not tedious fight, but in the second encounter, it drops bombs that bounce towards you, and has a longer period of time before it becomes vulnerable to attack.
* Bamboo Pandamonium. He's tall enough that you can't get behind him without taking a hit, and has attacks that take up big chunks of the screen. Also, when he takes enough damage, he will try to lunge at the player, [[OneHitKO which is almost instant death if it connects]] if you don't have any Life Ups. It's more bearable with the Ride Armor...[[GuideDangIt if you knew you could take it with you to the boss.]] And you don't have access to it at all in the BossRush, so good luck with that. Oh, and Zero's technique that's strong against him is...a downward stab from the air (which puts you into a big risk).
* [[spoiler:Lumine]]. He comes after ThatOneLevel, and is fought directly after Sigma, who's hard enough to begin with. He has two forms; the first one uses the Overdrives 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, the walls are off limits. 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 {{Bullet Hell}}-like laser attacks (one of which lasts a long time and then ''comes back in reverse''), has no notable weakness, and is difficult to get a bead on. On his trump card, he triggers [[DesperationAttack Paradise Lost]], which will outright [[RocksFallEverybodyDies finish you off]] if you don't do the same to him in 30 seconds. And the player has to know they had to [[spoiler:[[GuideDangIt have Axl finish him with a Doubleteam as a prerequisite for the secret ending]]]]?

[[folder: ''Mega Man Legends'' series]]
* 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, [[NonStandardGameOver 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. It's tame enough that you can get by with just your buster in Normal if you know what you're doing, but on Hard the entire thing basically mandates a maxed out Machine Buster and Hyper Cartridge to refresh your ammo for it.
** The battle against the Gesellschaft takes this UpToEleven. You have to fight several Draches, the Gesellschaft itself, and then the HumongousMecha Focke-Wulf, one after another, with no continue points or opportunities to heal. You have to do it from the top of the Flutter, which is a small confined space and offers no defensive cover. The Flutter ''itself'' can take damage, there's no way of healing it, if it's shot down it's GameOver, and the ''enemies specifically target the Flutter over you''. You're also ''cut off'' from the town and any resources since the boss fight happens ''as you are leaving the dungeon and returning to town''. It is [[UnwinnableByInsanity technically possible]] to sabotage yourself so badly that you have no chance of winning, but fortunately even without being able to go back to town, they are very possible to take down by developing [[MoreDakka superior firepower]].
** What's especially aggravating about the Focke-Wulf is that if you get hit by one missile, you're pretty much guaranteed to get hit by all the remaining ones as well since they're fired so close together.
* The Karumuna Bash trio, three doglike Reaverbots in the Sub-gate of the Clozer Wood. Those things are ''nasty'' if you're not CrazyPrepared 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 CameraScrew 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.

!!''Mega Man Legends 2''
* The train battle. You have to chase down the enemy train, taking on each independent train car as its own separate boss, all the while protecting your own train from an inane amount of artillery and homing missiles. When you finally reach the engine, even a shot ''from the most powered up weapon in the game'' barely drains a slight sliver from its health bar. All in all, the fight takes about ''two solid hours'' of holding the fire button and dodging projectiles. And if you die, even at any part, it's back to the beginning of the fight.

!!''The Misadventures of Tron Bonne''


[[folder: ''Mega Man Battle Network'' series]]

!!''Mega Man Battle Network''
* In a game with mostly easy bosses, [=MagicMan.EXE=] sticks out like a sore thumb. His main attack is a slow-moving flame that hits like a Mack truck, but what truly pushes him into this territory is that he's also a FlunkyBoss. He can summon up to two normal viruses at any time, and the types he summons are those that have difficult-to-dodge attack patterns (''especially'' when you've also got [=MagicMan=]'s attacks thrown into the mix), and because they'll be replaced as soon as they die, destroying them isn't even really an option. If you've been relying on your alphabet soup folder to get you this far in the game, prepare to keep on dying over and over again.

!!''VideoGame/MegaManBattleNetwork 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 [[ShapedLikeItself 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 WakeUpCallBoss... Worse yet, it's ''entirely'' possible for the game to be UnwinnableByMistake here, as you can't leave his area (either to recover HP or improve your moveset) once you enter (but nothing stops saving...)
* [=ThunderMan.EXE=] remains in the back row, and fields 3 thunder clouds that move back and forth the rows. These can fire off paralyzing thunder balls, and attack [=MegaMan=] if their movement gets obstructed. This results in the player needing to do some fancy footwork to be able to land hits on [=ThunderMan=] while dodging the clouds. And due to plot circumstances, the first time you fight him, you have also lost all your chips with exception to your folder, and you can't access the net to get new chips unless you beat him. In the Virtual Console rerelease, he has the potential to be ''even worse'' if the player has relied on the Gospel Breath chips (which can't hit anything in the back row) and hasn't upgraded the chip folder from time to time.

!!''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 [=WideSwords=] 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 [=MegaMan=]. 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 GoddamnedBoss status. You can't even ''find'' him unless [[spoiler:you have less than 1/4 of your max HP.]] Frickin' bastard.
* [[http://megaman.wikia.com/wiki/KingMan.EXE KingMan.EXE]] 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, which means no [=AreaGrab=] or powerful direct and melee attacks. 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' auras can compare to this guy's cheapness. But it's okay, break-type chips can destroy his chess pieces...just kidding, the chess pieces are only incapacitated temporarily. If you figure this out and try it, he'll use a different and more vicious set against you.
* 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.
* [=FlameMan.EXE=] 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 [[ColorCodedForYourConvenience 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 varieties of flames lit, which means he can be recovering HP AND invincible at the same time. And his attacks are designed to take advantage of this.
* You have to fight Bass twice in the storyline, though the first one is just a HopelessBossFight (you can't hurt him, and even you use something that makes you invincible, his attacks ignore it). The second fight, however, is a pain to get through, because he still has his Life Aura, and he attacks ridiculously hard, so it may take you a few tries if you don't have the right chip folder, and he comes right before you fight [[FinalBoss Alpha]], which if you lose to, you'll have to fight Bass AGAIN.
** What makes these two fights especially annoying that Bass has an Aura that can only be removed temporarily using an attack with over 100 power (permanently with a near-impossible to obtain chip), while Alpha has a shield that requires multiple consecutive hits to remove. Hope you brought a deck with both high damage ''and'' rapid firing chips!
*** Though Bass is somewhat easier compared to [=BubbleMan=], [=DrillMan=], and [=KingMan=]. Breaking chips are not common until ''4'', and those chips would help a lot against those three. Bass has no such resistance; Life Aura can be chipped away by any strong chip or North Wind (blows auras away).

!!''Mega Man Battle Network 4''
* [=SparkMan.EXE=] is very difficult to land hits on, as he keeps vanishing off the battlefield, and is vulnerable for very short moments. If the player faces him in the first playthrough, it's also likely a lot of their chips will get blocked by the mines that [=SparkMan=] sends out once they line up with him.
* [=ThunderMan.EXE=] returns for Red Sun, trading his three thunder clouds (detailed above) for one that circulates the perimeter of the field. This time, the thunder cloud will fire paralyzing thunder balls whenever [=MegaMan=] lines up with it horizontally or vertically, so if you stand in the wrong position it can stunlock you for a short time.
* Duo's Meteo Fist 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 NewGamePlus 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 NewGamePlus, he'll have his health scaled up to truly ridiculous levels. A MarathonBoss 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.
** Let's also not forget that Duo's battle terrain turns his 2 back columns completely empty, meaning panel-reliant chips like the [[GameBreaker game-breaking]] Air Hockey are ineffective.

!!''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 [[TheComputerIsACheatingBastard can take infinite punishment from time-stopping Chips.]] He can also hide in a cloud while summoning a [[AdvancingWallOfDoom pillar of clouds that chases you around]], and the pillar remains even after [=BubbleMan=] stops hiding.
** Even in a Liberation Mission, [=CloudMan=]'s field attack is equally frustrating. Anyone hit by this attack gets ''paralyzed'' and will not be usable for the next 2 turns, thereby slowing down your progress on defeating him once you are in position to attack him directly. Even if your Defense Navi can negate the damage done by this attack, it won't negate the paralysis.
* Nebula Gray. It has a huge repertoire of devastating moves; it has one that, like Duo's Meteo Fist, can leave your entire side of the field broken, another that ''drains your HP and restores its own'', plus it also has a passive attack just to keep you on your toes. It can only be damaged by hitting the blue flame that orbits it, making it entirely possible to line up an attack and then miss. It also can summon Dark [=MegaMan=] to use some attacks of its own on you, which can potentially do ridiculous damage should it hit a Soul's weakness. Not to mention one of them stuns you, making it that much easier for the other attacks to hit you. Fun!
** And just like Duo, Nebula Gray's 2 back columns are completely empty, forcing the player to adjust their strategy if their previous tactics used panel-reliant attacks.

!!''Mega Man Battle Network 6''
* [=CircusMan.EXE=] can prove to be a very frustrating boss fight, especially in the rematches where he gets stronger and faster. Like many others of his kind, he remains in the back row, forcing a player to use Area Grab to even get close enough for short-range chips. He moves by hopping around, creating many brief moments where any attacks would miss, and his own attacks are pretty fast and execute themselves multiple times in succession. His ultimate attack has a short animation and if it connects, it leaves [=MegaMan=] with a status effect that makes it difficult to dodge his other attacks! What this amounts to is the player doing some fancy footwork to dodge all the attacks while desperately trying to land their own.

!!''Mega Man Network Transmission''
* [=GutsMan.EXE=] is laughably easy in the main series games, but a complete and utter nightmare in this one. He lumbers around slowly, but his attacks come out fast: he likes to smash the ground with the Guts Hammer which creates a shockwave with an enormous amount of range, and if you try to slide under him when he gets too close he's quick to spin around and nail you with a powerful punch. They're his only attacks, but they deal a ''horrifying'' amount of damage and will murder you in no time flat.
* [=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, [=BrightMan=] 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 WakeUpCallBoss.
* [=StarMan.EXE=] isn't one of the bosses that can shield your attacks, but he compensates that by teleporting around and floating out of range most of the time, not only that, but one of his two attacks involves dropping meteors diagonally on the screen, sometimes being even impossible to dodge and he LOVES to spam them, and every time he uses the attack he also teleports. It gets even worse when he's on low health, because he drops A LOT more meteors that fill most of the screen and are almost always undodgeable, and if anything he likes to spam them even more at this point.

[[folder: ''Mega Man Zero'' series]]

* Aztec Falcon, the [[StarterVillain first mission boss]], is seemingly insurmountable the first time you fight him. You have no charge attack (unless you spent time grinding it out by going back to the Underground Lab; 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, if you're not aiming for the tiny hitbox that is his head. Ah, yes -- did we mention he is also a ''TimeLimitBoss''?
* 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 DopplegangerSpin 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 DesperationAttack 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 KaizoTrap ability in the second battle.
** Amusingly, by the time you get to face him again in the third game, there are several upgrades available (ie, Shadow Dash) that render him a pushover.
* Then the Rainbow Devil shows up. 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.

!!''Mega Man Zero 2''
* Phoenix Magnion is plain ridiculous. He has an arena which periodically 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 time. What's worse, he ''dodges every attack'' if he's sitting still. 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.
* 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 a long and grueling ThatOneLevel. And he has an attack which cannot be avoided, meaning you have to get him to change his flight path. 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. [[GuideDangIt As if you're just supposed to know this out of hand.]] And he'll keep using this attack until you die.

!!''Mega Man Zero 3''
* Cubit Foxtar. She's able to fire her fireballs in several intricate ways, and especially if you hit her with a lightning attack, she'll transform into 5 "ghost flames" that will then fly around the screen in a pattern that requires you to time your dashes; she's invulnerable when she does this.

!!''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.
** He's also fought in an open area with no walls, so there's no wall jumping away from him.
* Heat Genblem, a fire-based turtle Reploid who has invulnerable periods while spinning with a fiery shell and ricochets off walls to hit you. His most damaging move is a laser that circles the entire screen multiple times, the only way out of this being to display extremely fancy footwork and use the walls to loop up and around him.

[[folder: ''Mega Man ZX'' series]]
* Serpent's two forms on hard mode. This sounds like a given, but you're lucky to survive more than two hits from much of anything in this mode, which also means [[ThatOneLevel just reaching the end of his level is an ordeal]]. His first form was made eye-poppingly fast, and while the second form is only minimally altered, you'll still need almost a perfect run to win.

!!''Mega Man ZX Advent''
* Basically every boss in this game elevates to this level in [[BossRush Boss Survival mode]]. You're given only the default-length life and weapon gauges, two sub tanks, and a single life to try and kill 16 bosses in a row. Damage carries over between fights, so for the most part if you get hit more than once before getting to the Enemy Mega Men -- and that's 8 full boss fights to that point -- you're probably screwed. With such little room for error, suddenly the game's more abuseable techniques (Time Bomb, ZX spinning slash, ect.) don't seem so broken to spam.
* 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 [[GameBreaker 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 exploding icicles at you from the background, then rewinds them to un-explode and hit you again.
** Even worse? He uses Time Bomb ''again'' right before he uses that attack. The good thing? The ones used at the start of those attacks can actually wear off (only after he's done with the attack, of course) and he only uses it twice, once at slightly beneath half health and the other about two charged shots before death.
* Aeolus. Not for his relatively tame attack pattern, though [[StealthPun lightning reflexes]] might be needed to get out of his slashing attacks (the brief pause between all of his moves can sometimes get you pinned into a corner if you're not careful). No, the issue is his ultimate attack that he loves to use and abuse: he floats up in the corner of the screen and traps you between two lightning pinwheels that spin in the same direction. Once he starts this, you can't stop it, and from the ground, you have little choice but to try and dash between the uneven lightning rotation (good luck). You can certainly trivialize the attack itself if you turn into Queenbee and fly up fast enough (assuming you haven't already burnt up the weapon gauge), but then you still can't even ''hit'' Aeolus until he drops to the ground. By extension, this makes [[GameBreaker Time Bomb]] unhelpful. All in all, he's a surprisingly savvy bastard.


[[folder: ''Mega Man Star Force'' series]]
* Gemini Spark can be particularly painful to fight, especially if you're playing the Pegasus version where your version's SuperMode becomes weak to their attacks. Despite it looking like a DualBoss, you have to defeat ''only'' the black Gemini Spark to defeat them both. Any attacks on the white Gemini Spark are wasted. All in all this results in a chaotic battle with the player frantically dodging attacks coming from both Sparks while trying to aim only at black Spark.
* A battle with [[DualBoss three]] level 3 Jammers happens during the endgame. They have above-average HP and fast attacks. While not too complex, they can overwhelm and quickly end you with their punches and machine guns if you make mistakes. If you die, you may even lose some progress because the battle happens [[DifficultySpike out of nowhere]] during a long period without Geo asking to save the game.

!!''Mega Man Star Force 2''
%% Rogue SX doesn't actually count, no matter how much you want to add him; Bonus Bosses are overpowered on purpose.
* Le Mu is the greatest nightmare of the three Star Force Final Bosses, because the field is a storm of activity. In his first phase, Mega Man has to break open the seal down the front of Le Mu's chest, which is hard when Le Mu is launching giant drills out you, tearing open damaging portals all over the field, summoning Murian soldiers to attack you, or shooting at you with machineguns. Once you break open the seal on its chest, well, then things ''really'' get started. You still have to shoot at its core, but now it's moving around, attacking twice as fast and twice as hard, and it even has extra attacks, a pair of Big Fricking Swords and a WaveMotionGun! (Have fun!)

!!''Mega Man Star Force 3''
* Acid Ace. 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.
* Similar to the Jammer fight above, there is a fight with two Noise Wizards, one level 3 and one level 4[[note]]they go up to 6, but 4 is the strongest until the postgame[[/note]]. The level 4 one has an attack that cracks panels, so you can easily run out of room to dodge and just get barraged constantly by their sword and gun attacks, which they can combo between and just constantly put the pressure on you. It can be shocking how difficult this fight is, because Noise Wizards aren't usually a threat when fought one-on-one.
* Although the Crimson Dragon is considered one of the easier bosses in the franchise, the sheer amount of activity on screen can be stunning for newer players. You're always attacking, dodging, or blocking, with little to no breathing room in between. He also has the annoying mechanic of having to destroy his head every once in a while (recycled from Battle Network's Alpha) to damage the core, which can end up soaking an extra 800 or so damage over the course of the fight. His Sigma version drives this up even further with an even larger health pool and even faster attacks, making it hard to get an attack in without recovery chips and Super Armor.
* Apollo Flame. (He's also in the second game, but he's the final BonusBoss there as opposed to being fought halfway through the postgame.) He has a lot of HP, a barrier that regenerates, and a lot of attacks that either can't be blocked or keep you from hitting him until his barrier comes back. It's easier if you have Cancer or Virgo Noise, and infinitely harder if you have Ophiuca or Wolf Noise.

[[folder:Fan Games]]
* Jet Man. He spents most of the fight out of your reach, and he has lightning-fast missiles and a whole cargo load of bombs in his arsenal that require precision and perfect timing to avoid. Good luck doing a NoDamageRun against this guy!
* Glue Man fights a lot like Concrete Man from ''Mega Man 9''. He fires Glue Shots at you to freeze you while at the same time sliding all around the arena trying to ram you for MASSIVE CollisionDamage.
* Comet Woman isn't too bad in her first fight, but she becomes exponentially harder in the BossRush. Without the low gravity from her stage, she's able to move much faster, her orbiting shield attack becomes harder to avoid, and you'll spend more of the fight with those orbiting balls around you blocking your shots.
* The GiantEnemyCrab from Occupied Wily Stage 1. It pays homage to the Mecha Dragon from ''Mega Man 2'', but ramps the difficulty UpToEleven. You have to use the three ladders to avoid the energy balls the crab shoots out, but it also has another attack where it electrifies one of the ladders. If you get hit by anything while you're on the ladders, the knockback will push you right into the pit, and there's no safety platform like the Mecha Dragon fight.
* The squid boss from Occupied Wily Stage 2 has a OneHitKill move where it rams its head (which you have to stand on in order to fight it) into the ceiling, and it requires a precise jump off to the side of the boss gate in order to avoid it. The later you jump, the more likely you will be to hit the ceiling and fall into the pit, but if you jump too early, the squid will be too high to catch you. Even then, you're still fighting it on a small platform with bubbles from its mouth and plasma balls from its tentacles, making it very easy to get hit and even then you could still get knocked into a pit.
* The Wily Machine is probably the hardest version of Wily since his capsule from ''Mega Man 7''. The first phase has a weak spot that is out of reach of the Mega Buster, so you need an upward-reaching weapon to hit him, and he takes up about ''three fourths of the screen'', giving you little room to dodge his attacks.
** The second phase is even worse. The Wily Walker's weak spot is only visible for a couple seconds when it jumps, and it's random where it's going to jump next. Each time after it jumps it will charge at you. If it jumps all the way to the other side of the arena, it will dash at you, and you can slow it down with the Mega Buster in that case, but if it lands somewhere in the middle it will just walk at you which can't be slowed down. If you're not behind it when it does this, you need a perfectly-timed Comet Dash or Rush Coil to avoid it.

* The first phase of [[spoiler:the Remir Machine]]. The only way to damage it is to turn on the spikes in the room and get it to step on them, while at the same time avoiding its two massive hitboxes and the bullets it fires from the top of the screen, and also making sure ''you'' don't fall into the spikes.

* The Fusion Masters that you fight is dependent upon which one of the first eight you defeat last; meaning you may or may not have to fight War Man, who fights somewhat like Sigma from the first ''X'' game. He has a shield that allows him to deflect any attack other than Crypt Cloak (even his Rock Force weakness, Knight Crush, gets deflected), and this shield is only put down for a second when he attacks (which he will only do if you get within a dangerously close range). He's too big to jump over, and deals ridiculous amounts of damage with his attacks. He also deals a lot of contact damage, and can easily stick you in a corner if you're not ready for a fight against what is basically a giant Sniper Joe.
* If you don't get War Man, the other set of Fusion Masters has a nasty fight in Flare Man. Similar to Stone Man from ''Mega Man 5'', he jumps around the room, stunning you whenever he lands unless you jump. ''Un''like Stone Man, ''his other attacks'' also stun you when he starts them, which can really mess up your timing when dodging them. He's also one of a few bosses who's actually harder to fight with Mega Man than his Rock Force weakness; Crypt Cloak is hard to hit him with because it's ground-based and he jumps around a lot, but Nitro Man can throw the Wheel Cutter in multiple directions.
* Regardless of which set of Fusion Masters you fight, once you beat all four your next stop is Death Man. He's not a very complex boss but he makes up for it by doing ''absurd'' damage with his attacks, which kill from full health in just three hits!

!!''VideoGame/MakeAGoodMegaManLevelContest 2''
* The three bosses of the [[ThatOneLevel hated]] Yggdrasil level are just as fiendishly difficult as the stage itself for all the wrong reasons: unnecessarily huge health pools, unpredictable AI, and outright unfair attacks. It's worth noting that in a game with more than it's fair share of difficult bosses, they're among the few ''outright excluded from the arena challenges'' due to being so ridiculously annoying to fight.
** Crator is considered to be the toughest of the three by far. He spends a lot of time deflecting your shots, is incredibly aggressive and prone to getting in your face, and has attacks that lop off around half your health at best or one-hit kill you at worst. Even his weakest attack, a series of energy bursts shooting up from the ground, makes up for it's lacking strength by coming out fast and being incredibly hard to dodge. To make things worse, his weakness to the Slash Claw does little to mitigate the difficulty of his fight since its lack of range means you have to constantly put yourself in danger of being effortlessly slaughtered to use it.
** Cream is no slouch either, since she has an instant death attack of her own that comes out way too fast for its own good, and loves to jump around the arena like a spastic monkey, and has a ton of projectile attacks that can be hard to dodge since she has no tells indicating what she'll be firing at you.
** And while not as bad as the above two, Kichona is annoying to fight all the same due to not only possessing a whopping two health bars, but also being able to restore her health with her syringe attack. She can also randomly glitch her way out of the fight and make it flat-out unwinnable.
* While severely toned down from how ridiculously hard he was in his [[RockmanCX home game]], Cheat Man is among the hardest tier bosses. He can hit you with damaging text before the fight even begins, and spends the entirety of his boss battle behind a shield that drops your attacks on you if you end up hitting it. He also constantly has large projectiles bouncing around his arena, which he will happily attempt to glitch you into falling into them multiple times in a row. Even worse, he has a powerful beam attack that will cause you to drop to one health if it hits, and there's a delay before firing just to trip you up.
* Autobounce, the boss of Wily 4 (which itself is ThatOneLevel). Good news: You get unlimited ammo on all your weapons for this fight. Bad news: Autobounce can only be hurt by one at a time, represented by its color scheme (which changes after each time it takes damage). Its attack in the Grab Buster form heals it if it connects with you, the Sakugarne form is nigh-impossible to hit without taking damage, and the Slash Claw form moves faster and faster until you're able to hit it (which, again, is near impossible to do without getting hit yourself). Plus, as its health goes down, its attacks and movements get faster.

* Dagger Man. His attacks involve daggers, and his attacks deal tons of damage. You will most likely get hit by his attack where he dashes and then sends cutter waves two times. It's very easy to be hit by this attack. Even with your Mega Buster's charged shot upgrade that can be bought, Dagger Man has another trick up his sleeve; he also teleports before two of his main attacks and after he shoots his Flash Dagger, meaning if you don't have his weakness, this teleportation can be annoying if you've charged up your Mega Buster and he teleports away from your shot, (even when he teleports right behind you) even when he is about to use his dash attack. There is also the attack where he shoots three daggers down, and it is easy to get hit by the dagger he shoots down while you are avoiding the shockwaves, leaving you screwed.
-> ''(pow-pow-pow-pow-pow...) \\
[[http://www.youtube.com/watch?v=FAXJ3XUIXWk GAME OVER]]''