History ThatOneBoss / SuperMarioBros

The first phase summons three flunkies. Because of the choice of flunkies, very few stickers will take out all three at once. On top of that, whenever one's killed, even more are summoned. The second phase has a giant Whomp. Whenever it's up, [[StoneWall Bowser will take only 1 damage from anything]]. It also hits twice for 10 damage, on top of Bowser's barrage of attacks. On top of that, only one kind of sticker will knock it over and make it vulnerable to Thing Stickers. The third phase, Bowser uses only one attack, but [[ThatOneAttack it's a doozy]]. He summons a barrage of fireballs which are impossible to block completely. Using the proper Thing Sticker won't work permanently. The fourth phase can be ended in one move, but if you can't, you'll have to deal with an invincible enemy in front of Bowser. The final phase? HopelessBossFight, yes, but his attacks hit for horrendous amounts of damage. The third move is a devastating combo that will crumple you for 3 turns if you get hit with the final blow, at which point [[YouAreAlreadyDead you can just shut off the 3DS.]] Oh yeah, and his fire attacks can destroy your stickers.

** Fryguy, the flaming entity fought in World 4. At first, it seems like you simply have to hit it with the mushrooms three times, and technically that's the idea. After that, however, it splits into four living fireballs that hop here and there, trying to hurt you. And the more fireballs you kill, the faster the remaining ones will move. Granted, it's possible to kill them all in one hit, but good luck with the timing. To make matters worse, the game has a glitch where if you touch the last fireball before it dies, the door to the next world might not appear. You can escape having to reset by using a code that kills you, but that just means you have to try and beat this boss from the beginning.

** Croco's rematch in the Coal Mines can be a pain. He's proportionately as strong as the first time relative to the point of the game you're in, but when his HP gets low, he'll steal your party's items and start spamming Chomp, an extremely powerful physical attack with some wonky timing to defend against. Without items, your only source of healing is Mallow's HP Rain, but if you were careless with special attacks up until then then you're probably low on FP for it and have no way to recover FP now. For that matter if Mallow or anyone else dies, you have no way to revive them.

** Yaridovich. Right after you get the star from the Sunken Ship and return to Seaside Town, he takes it and you have to beat him to get it back. So how tough is he? His health and attack are both extremely high for that point in the game, he has powerful magic attacks that like [[MakingASplash Water Blast]] which hit your ''entire party'' for massive damage, and he can also put negative statuses on your characters for good measure. If that's not enough, he can also duplicate and use his moves ''twice in a row'', and only the real one takes actual damage until he decides to heal himself. When the duplicate is eventually destroyed, he can bring it back and make the fun start all over again. This is a sign that [[WakeUpCallBoss the game isn't messing around anymore,]] and that constantly attacking over and over again isn't going to win every battle.

** Watinga in the Gnat Attack minigame. You only get thirty seconds to beat him, and periodically throughout the fight, bomb flies fly in, and if they're allowed to explode, it takes a second off of the timer each. Not only that, but Watinga also summons several flies and leaves the screen, and will only return once they're all swatted. Finally, he takes an ungodly amount of taps before he dies. Can you see where this is going? And Hard Mode has ''two Watingas''.

Bosses in ''Mario'' games [[BreatherBoss rarely pose much of a challenge]], so it’s easy to come to view them as glorified cool-down exercises after [[ThatOneLevel the sheer hell]] you probably went through [[HardLevelsEasyBosses just to reach them]]. Then you stumble across one of [[ThatOneBoss these guys]] and wind up with your hat shoved down your throat.

** For a boss so early in the game, World 2's Roy Koopa can be a bit of a nightmare to get used to. He ground pounds, stunning the player for several seconds so that when they recover, they only have a few frames (if any frames at all, depending on how close they are to him) to dodge his magic. Morton of World 6 can also stun the player for a few seconds, but not for as long. However, his tower boss has lava, spikes, his fast spinning shell and tight spaces to make up for it.
** Wendy has essentially the same fight as in ''Super Mario Bros 3'', but ''underwater''. Obviously you'll have to fight with water physics hampering your ability to dodge her attacks, but there's also the fact that until the water temporarily recedes, there's no way to hurt her unless you have a Fire Flower with you.
** Ludwig. He flutter jumps and gets a good aim at the player to land on them and hurt them. In his first fight (which is already a huge pain to even get to) his magic also chases you, and in his second fight, you have to constantly move between three tiny platforms.

** The Axem Rangers are plenty tough, considering there are five of them, and each one has a different variety of attacks — Red and Yellow hand out massive physical damage, Black counterattacks ''everything'', Pink [[TheMedic heals]], and Green blasts you with powerful magic spells. And even after beating all of them, [[SequentialBoss they combine]] with their Zord/warship thing for one more go, using the insanely powerful [[WaveMotionGun Breaker Beam]] attack, which does about 70-90% of your character's maximum health.

** While Bowser's battles are no cakewalk, his secret and final rematch after collecting all Power Moons can be especially tough without a Life-Up Heart. In the previous fight, he tossed breakable brick boulders or flaming, indestructible golden boulders modeled after his shell. Here he primarily throws the latter as frequently as he can, and the brick boulders roll by so quickly you'd be lucky to smash one. He also takes ''far'' more rounds of punches overall, and his fire breath attack can take several attempts to fully wrap your head around, as he does it for a longer period of time and moves in hard-to-predict directions.

** Fought separately, Hisstocrat and Queen Hisstocrat are bearable bosses (and, in the opinion of the fans, [[Awesome/VideoGameBosses very enjoyable to fight]]). But that changes in the BossRush level in World Flower, because you'll have to deal with both of them in a DualBoss fight. Them commanding the raining fireballs (King Hisstocrat originally couldn't do that) and the summoning of snakes at the same time makes the battle more complex as well as longer (and you still have to deal with the other bosses present, including Motley Bossblob — which ''once again rises in difficulty'' — in a time limit of only 500 seconds). The only easy way to deal with them is by hitting them at the same time at every opportunity, but that requires precise maneuvering with the moves of the Cat powerup. Another trick is jumping off the lower leveled plates (which does not require the cat suit). You may also consider bringing a Tanooki Suit (or somehow use Peach's flotation or Rosalina's spin-jump) to fly over to the other Hisstocrat's head, but you may find it hard to be able to ''keep'' the Tanooki Suit with their attacks.

** The secret rematch with Bowser can be tough without a Life-Up Heart. In the previous fight, he tossed breakable brick boulders or flaming, indestructible golden boulders modeled after his shell. Here he ''only'' throws the latter, and frequently so. He also takes more rounds of punches overall, and his fire breath attack can take several attempts to fully wrap your head around, as he does it for a longer period of time and moves in somewhat unpredictable directions.

* ''VideoGame/LuigisMansion'':

* Want to fight the bosses of ''VideoGame/NewSuperMarioBrosU'' without [[CycleOfHurting hitting them immediately after they get up?]] Iggy and Roy become a nightmare. Iggy will walk onto the ceiling and use magic to create Magmaarghs. After dodging them, you have to run next to the floor where Iggy is and wait for him to fall, then immediately attack. Then, Roy has a double sided Bullet Bill cannon and jumps between floating, moving platforms.

** Watinga in the Gnat Attack minigame. You only get thirty seconds to beat him, and periodically throughout the fight, bomb flies fly in, and if they're allowed to explode, it takes a second off of the timer each. Not only that, but Watinga also summons several flies and leaves the screen, and will only return once they're all swatted. Finally, he takes an ungodly amount of taps before he dies. Can you see where this is going? And Hard Mode has ''[[UpToEleven two Watingas]]''.