- Queen B in the first Donkey Kong Country game mainly because she is fast and has an erratic movement pattern. She has a good amount of health, and when she takes enough damage, she Turns Red and becomes even faster and much more erratic, which means you have to have quick reflexes to defeat her. It's even harder in the Game Boy Advance version, as you need to deal with the zingers she summons before you can attack her, as she is red until you get rid of her babies.
- Donkey Kong Country 2: Diddy's Kong Quest:
- King Zing continues the trend of hornets being tough bosses, mostly because you play as Squawks, who is one of the hardest animal buddies to control. You have to shoot at his stinger (which is very tricky due to it being located on his underside and Squawks' Abnormal Ammo being affected by gravity) six times, all the while trying your hardest to avoid getting hit by his stinger projectiles and him running into you because of how difficult Squawks is to control. But it doesn't end there — then he splits into regular-sized Zingers, the last of which you have to hit three times while it homes in on you.
- Kreepy Krow, the ghost of the first boss Krow, mainly because you have to avoid his deceased minions diving at you before you can even attack him, and when you hit him, he flies away and you have to climb up after him, dodging several lightning-fast cannonball shots from every angle. You best hope you don't lose Diddy Kong before you have to take on the climbing sections, otherwise you're in for a heavy heaping of pain.
- Donkey Kong Country 3: Dixie Kong's Double Trouble!:
- Barbos. First of all, this fight takes place underwater using Enguarde the Swordfish, which should already tell you something right there. Second, Barbos is a giant Lurchin, which is an underwater creature that can hide inside of its spiked shell and is only vulnerable when it peeks outside for brief intervals, meaning that you have to be quick when you attack her. Third, she has two protector Lurchins in her first two phases which can't be killed directly. The only way to damage her in the first phase is to hit the Lurchins so they bounce off the wall and take out her protector Lurchins, allowing you to hit her while she's unguarded. In the second phase, you have to trick her homing shell-missiles into killing the protector Lurchins. The final phase has her firing five spikes in a spread pattern. You have to stand in just the right place to dodge them.
- Squirt, the third boss, also counts for this and doubles as a Wake-Up Call Boss considering that you have to fight him as Ellie the Elephant, and gather enough water from the waterfall with her trunk to shoot his eyes shut when he pops out of the waterfall. Squirt only has one attack, which is making a large water spout with his mouth. This doesn't hurt you, but it can push you off of the tiny platforms surrounding him and into the bottomless pit below you, which instantly kills you regardless of whether or not you have both Kongs. It isn't necessarily that Squirt is that difficult to avoid, it's more like there is no margin for error whatsoever - if you slip up and overshoot the ledge or fall behind while trying to reload your water pellets, there goes a life. Couple this with the fact that he takes quite a few hits before he surrenders, and you'll have quite a challenge to deal with, especially considering that this is in the first half of the game.
- Arich is also an immense pain. He bounces all over the place and shoots a lot of bouncing green venom balls that move just slow enough and in such numbers that dodging them is an ordeal. You have to beat him by throwing barrels at his head — to get to said barrels after the first one (which appears on top of him), you've got to carefully jump on his body to reach it. And you have to be spot-on to hit his head. Landing the final hit is especially tricky if you're playing as Dixie - the barrel gets destroyed when it hits a venom ball, and Arich's final pattern is tricky enough to dodge without carrying an object that effectively doubles the size of your hitbox vertically.
- If you didn't bother playing the target-shooting sidegames, Bleak will give you hell. He's fought in the style of said sidegames (which makes it even greater hell if you've only played the GBA version). While it's easy to pick up on the mechanics, damaging him is not, as he only leaves himself vulnerable for about a second at a time, all while he's tossing lots of snowballs at you. Then he goes into phases where he shoots snowballs from his hat, which slowly get faster and fire in more complex patterns, requiring quick dodging to survive — and when the barrage is over, you have exactly one second to make the hit. You can take two hits before having to start all over again.
- Donkey Kong 64 has four of these guys: Mad Jack, Puftoss, King Kut-Out, and the second fight with Dogadon.
- Mad Jack just looks pants-wettingly terrifying, and that's not the worst part; you're forced to fight him on a set of small pillars which must be navigated by using Tiny's Helicopter Hair technique, and if you fall off, you have to sit and wait while Tiny gets dropped off at the top again using a small elevator. He constantly throws fireballs at you with crazy precision, and to damage him, you have to Ground Pound one of two switches placed randomly on one of the many pillars scattered throughout the room (you have to hit the one that corresponds with the color of the platform he's standing on, or else you get zapped). After that, he ducks back into his box and you have to avoid him while he jumps at you, and he can catch up to you pretty darn fast. If that isn't enough, he eventually turns invisible, and can jump even faster, and if you don't keep jumping restlessly away from Mad Jack, he WILL knock you off the platforms. Mad Jack is insensibly cruel, and, to many a fan's dismay, he's only the third boss of the game. And before the invisible phase, he shoots lasers that will activate any of the shock platforms regardless of if there's a switch or not.
- Puftoss, the game's fourth boss, is also a pain in the ass. Not only is he a Pass Through the Rings boss, but you don't even fight him on land; instead, you control Lanky in a tiny wooden boat with finicky controls. His arsenal includes surrounding himself with a giant spreading blue aura of energy that is rather difficult to dodge while looking for the rings, rapidly spitting fireballs at you, raining down fireballs from the sky, and shooting homing blowfish at you. On top of all this, you're timed between going through the rings, and if you slip up (not hard to do because of the aforementioned energy ring), you have to start over from that phase of the fight. Good luck lasting longer than a minute.
- The second fight against Dogadon is probably the most difficult, because of the hard-to-accomplish objective and time limit to the battle. At first, the battle goes like his first fight, but he sometimes throws that nigh-unavoidable wall of fire at you. Once you've hit him a few times, he makes the platform start to sink, and suddenly you only have 100 seconds to end the battle before you lose. Then it's all dependent on your button-mashing as giant Chunky, as otherwise you'll never beat him in time, and the increasingly frantic music doesn't help either...
- King Kut-Out is a cardboard version of King K. Rool, with the ability to shoot lasers at you. You have to jump in each of the cannons on the island, pointed at a spot where King Kut-Out spawns, and shoot yourself at him. He's annoying in this respect because he never fracking stops moving, making him extremely hard to hit. To make matters worse, missing with one of your Kongs flings him/her into the void behind the arena, forcing you to swap out to another Kong, and if all five miss (not terribly uncommon considering King Kut-Out's erratic movement pattern), you lose the fight and have to start all over again. It gets even worse when King Kut-Out becomes an Armless Biped. At this point he travels along the arena one side per second. The only way to strike him is to wait by one of the cannons, figure out exactly when he's going to show up on that side you're facing and hop into the cannon as soon as he appears. If your timing isn't perfect, your Kong is sent flying off the stage. And King Kut-Out creates a hologram of himself just to confuse you during the second phase.
- Donkey Kong Country Returns:
- Thugly is a souped-up version of Mugly, and is far more aggressive. To damage him, you have to jump on his back, much like his counterpart. However, this is made more difficult by the fact that his back armor becomes red-hot and damages you if you jump on it — if you don't want to get hit, you have to jump at exactly the right moment and hold down the jump button for as long as possible, and you still might miss his back and hit the armor by a few pixels. Every time he Turns Red after 3 hits, the arena becomes smaller and his charges and shockwaves are faster, to the point where you practically need to jump the instant he moves just to dodge them. On the final wave? Not only is he super-fast, but he gains an attack where he shoots a fireball, which breaks into three smaller fireballs, one of which randomly turns into three more. Hard enough normally, he's a complete nightmare in Mirror Mode.
- Colonel Pluck. His mech is huge and slowly walks across the screen, and you carefully have to walk under the legs as it walks. Only problem is, sometimes it'll start stamping and rushing across the arena. Your only clue for this is a very subtle clue in its walking (if it picks up one of its feet slightly lower than usual, it's going to rush), and once it does so, there's a good chance you won't survive it if you're on the wrong side of the arena. Most of the fight takes forever and you have to rely on subtle clues for its attacks. And once you destroy the body, he will fly around and drop Mecha Mook chickens in formations that are difficult to dodge, he loves to swoop down, which is very bad if you're trying to dispatch all the robots by jumping on them, and he's only vulnerable for about a second at a time. Good luck on Mirror Mode.
- Suprisingly, Mugly can be this on Time Attack mode. Want to get that Shiny Gold medal? You've got at least 37 seconds to beat him, and he's got 3 phases. You practically have to choreograph your moves and exploit his Mercy Invincibility perfectly.
- Donkey Kong Country: Tropical Freeze: Fugu the Frightening lives up to his name. First of all, the entire fight takes place underwater. Even if you are used to the swimming controls, you have to watch your Oxygen Meter, although by this point you've probably collected enough coins to buy a few oxygen-refilling Blue Balloons. The entire stage is surrounded by sharp shells that will hurt you if you are swimming around too fast. Fugu will inhale water to increase his size, which by stage 3 will literally take up half of the stage. He will also release two types of enemies; pufferfish, which you can dash into to hurt him, and sea urchins, which can only be killed by Cranky Kong. You will have to avoid these enemies while fighting against a current that will try to push you against the sea shells. Fugu does have a weak spot behind him, but he'll be spinning around so much, pinpoint precision is required to hit him most of the time. Having Dixie on-hand will help avoid these obstacles (as well as turn enemies into extra hearts), but it's not a guaranteed victory. Plus, despite Funky Kong (in the Switch version only) having infinite air, don't assume that playing as him will make the fight easier.
That One Boss / Donkey Kong