The Legend of Zelda has Gleeok, a hydra monster found in three dungeons. He has multiple heads that can shoot fireballs from multiple angles, and when each head takes enough damage, it starts flying around the room to become an Invincible Minor Minion, which can continue to spit fire from even more angles while also causing Collision Damage. The other bosses are pushovers, but all you can do against Gleeok is stand your ground and hope you have a potion left.
Dark Link takes the cake in Zelda II: The Adventure of Link. He will block nearly every single one of your attacks, and manage to punish every single mistake you make. Not only that, he likes to jump on you and do Collision Damage even though you can't do the same to him. It also does not help that he's directly after another boss that requires you to use half your magic at best to even hurt it. Finally, lose all your lives, and it's back to the beginning of the Great Palace. The fight can be rendered a non-issue by exploiting his AI, but good luck figuring that out as a kid in the 80s.
And before him comes the Thunderbird. First, you have to use the Thunder spell to make him vulnerable at all (and one use of it will nearly empty your magic meter.) Then, you have to hit the small, exposed face of a giant bird-thing that will be spitting fireballs at you machine-gun style. Good luck, you'll need it!
Mothula holds the title in this game. Erratic movement, randomly-changing conveyor floor, randomly moving blade traps, and a three-beam attack that's hard to avoid if you're trying hard to avoid all the other perils. Worse still, a bug in the original SNES versions made him invulnerable to certain attacks of the level 3 sword and almost all attacks of the level 4 sword (The weak poke is all that works). Using the dungeon's item, the Fire Rod, works well so long as one doesn't run of of magic power.
Trinexx. You have to use magic attacks to defeat him, which is made a little more merciful by the fact that magic potions are generated in the battle, but still very hard. The worst part, however, is the freaking middle head that bobs out at you fairly often. This will be your downfall in the fight. He gives warning as to when he's going to do it, but even so, it's very difficult to dodge. And if you forgot to pick up the Ice Rod (the location of which which is hinted at by Sahasrahla, but it's found outside of a dungeon and it's in an out-of-the-way area so if you don't pay attention to his hint, you'll miss it), you can't beat his first form, making him unkillable. To add insult to injury, the Ice Rod's projectile moves very slowly, meaning Trinexx'll dodge your shot if given half the chance.
Helmasaur King, the first boss of the Dark World. He takes 25 (or if you use bombs during his first phase, which is more effective but much, much more difficult and slow, 13) hits to defeat. Meanwhile, even if you get as many heart pieces as you can in that point in the game, he can kill you in just 5 hits. If you don't take the time to get the maximum amount of Heart Containers, he can kill you in just three to four hits...assuming you don't take any damage on the path to him, which is filled with tough enemies.
Kholdstare, the boss of the Ice Palace. Although his second stage isn't particularly difficult, his first stage can only be hurt by the Fire Rod (a magic item), and if you haven't upgraded your magic meter it takes all of your magic to melt the ice. He doesn't drop any magic jars, so if you don't think bring a potion of magic with you or fill up your magic meter before the fight then you are SoL, as you will then have to let him kill you, refill your magic, fight your way through the whole dungeon again, and then try the fight again. Also, the Ice Palace itself relies on the Fire Rod very heavily, so the magic upgrade is basically a must-get before entering.
Moldorm. Every hit you do and every contact you make with him has knockback, and while it isn't a bottomless pit, it does knock you down to the floor below, where you climb back up and start the fight all over again. It's even worse in Link's Awakening, as the available space is smaller, and the area where you drop has no heart recovery. For all of this reasons, many people refer to it as Trolldorm.
Blaino from The Legend of Zelda: Link's Awakening, for a single charged punch from him will punch you back to the dungeon entrance. He's also almost impossible to hit except when he's preparing that charged punch (which only takes a couple of seconds to charge); if you don't stand in quite the right place while attacking him, he'll hit you and start the battle over. And he has a quicker punch that stuns you, allowing him to land his dungeon-exit punch on you all the more easily. And this guy is the miniboss.
The final boss, Nightmare, is also incredibly difficult. This guy has a whopping six phases, including a difficult game of Dead Man's Volley, an extremely fast version of Lanmola, a fight with Ganon, and a rematch with Moldorm of all people! The hardest part, however, is the last phase where you fight Dethl. This guy swings his long arms around, making it extremely tough to land a hit on his small eye. Even worse is the fact that his eye opens and closes every few seconds, forcing you to have near perfect timing. If you die, you have to start all the way back at the beginning.
Dark Link is particularly frustrating because he's only a miniboss. This is even worse considering that the actual boss of that level (That One Level through and through) can be much easier by comparison. And if you were hoping to use the Megaton Hammer or Din's Fire on him, they fixed that in Master Quest. You more or less have to beat him in a straight swordfight. A difficult duel could be fun, if there was some technique to it. But your quick-stab is useless (Dark Link jumps on top of your sword, then hits you), your jump attack is useless (Dark Link jumps to the side, then jump-attacks you), and he seems to dodge the spin attack, which leaves madly mashing the standard attack, which Dark link seems to do endlessly with the same speed while locked on, so the blows deflect each other. About the only way to beat him in a sword fight is to either use a non-standard weapon, like the Broken Giant's Knife or Biggoron's Sword, or go against every instinct the game has ingrained into you and turn off Z-targeting, which makes it harder for him to read your moves. Moreso, his HP depends on how many maximum hearts you have, so building up your health just makes the struggle worse. It does unintentionally make the boss much easier on three-heart runs, though.
Bongo Bongo. Firstly, he's invisible, meaning that you must use the magic-draining Lens of Truth to see him. Secondly, he constantly slams the arena with his palms, which causes you to bounce around, messing up your coordination. You can avoid most of the bouncing by wearing the Hover Boots, but those reduce your traction and practically turn the floor into butter, or the Iron Boots, which slow you down and make you a sitting duck for his punches and grabs. To defeat him, you must hit both of his hands in enough time, which is especially hard to do when you have three targets to deal with: his hands and his eye. When one hand is stunned, he'll attack you with the other, and you only have a short window of time to act before he grabs you and tosses you into the distance, giving his other hand time to recover. (By the way, did we mention that the floor around the arena is made of health-sapping poison?) If you DO stun both of his hands, his weak point, the eye, will open, and you have to react quickly again and hit his eye to incapacitate him before he charges you off the arena. Which can catch many players by surprise way too often. Finally, he has far more health than any other boss in the game, with around SIXTY HP. Hope you brought your optional and tricky-to-get Biggoron Sword!
This game has the hardest boss in Great Bay Temple (Gyorg). The reason is because it has a tendency to swallow the player right after he or she manages to hurt it, which requires the player to dive into the water, and it can only be avoided by reacting very quickly and returning to the surface. The remake changes it by having Gyorg float to the surface and expose its weak spot when it's stunned, allowing players to attack it from dry land. Gyorg also doesn't swallow players during its normal attacks. However, the remake adds a phase where Gyorg destroys the platform you're on, forcing the rest of the fight to take place underwater. Low on health? Hope the clusters of fish will give up one measly heart, because all of the pots that spawn in the arena only yield magic refills or arrows. The worst part is that you probably have wasted too much time trying to navigate the Great Bay Temple, so you'll most likely have a limited amount of time to fight him.
Great Bay Temple also has the most difficult miniboss in Wart, a giant moving eyeball that has over 40 bubbles surrounding it to shield it. Those spheres take two hits (one hit with the Gilded Sword) to destroy and after the first, they bounce around making the hookshot useless. And if you ignore the small balls, after enough hits on Wart itself they all fall off and start bouncing around everywhere, making the fight near impossible unless you take the time to focus on destroying the balls first, which takes ages.
Fighting Goht, which is a combination of Chasing Your Tail and as many hazards as possible, can get annoying. Goht is also annoying in that you need to defeat him more times than the other bosses for the 100% Completion.
Garo Master, one of the minibosses of the Stone Tower Temple. He's fast, hits hard, takes a surprising amount of punishment, and is nigh-impossible to hit in return. Unlike the normal Garos, trying to take him out by blocking his jumping attack and knocking his swords away won't work because he'll just bounce off your shield. Arrows won't work either. Even if you thought you could just back up, he swipes out with his swords when he attacks, which will hit you in front and to the side. Every time you're hit, you go flying back. When you manage to hit him, he'll follow up very quickly with a counterattack. His swords are covered in fire, so if for some reason you try to fight him as Deku or Zora Link, a single hit will force you to restart the entire battle. Sometimes he'll jump up and try to hit you from above (which is an easier way to hurt him than normally). You have to be really quick to get behind him before he gets back up. Also, in the Secret Shrine and the Moon rematches, his death animation can theoretically kill you if your life energy is too low.
In the Majora's Mask 3DS remake, all of the bosses had their mechanics changed. Twinmold became significantly harder: whereas, in the original, one could kill both the worms by hacking and slashing away at them with the Giant's Mask, the Giant's Mask here is unavailable until the first worm is defeated. You also don't get to use your sword with the Giant's Mask in the remake, meaning you have to kill the other worm by punching and slamming it... and all while your magic meter slowly drains. The red Twinmold specifically is what makes the 3DS version of the fight so difficult. The blue one isn't terribly challenging, but you're constantly being blindsided by the red one's fireballs while trying to take out the blue one with Light Arrows. Once you've donned the Giant's Mask, you have to first stun the red Twinmold by pummeling it with your bare hands; stunning it takes a good 15 or so hits, and the hit counter to stun Twinmold resets if it goes underground, a task made even harder by the fact that just about every one of his attacks knocks you down and forces you to wait for Link to stand back up after a few seconds. The arena does have three boulders that you can pick up and throw to instantly stun Twinmold, but Twinmold requires four stun-and-damage cycles to kill, meaning you're going to have to successfully stun him with punches at least once.
Gleeok returns in Oracle of Seasons, as do a bunch of other bosses from the original, but in OoS, he isn't the only boss that can try your patience, especially if you have the Biggoron Sword (which makes Gleeok's first phase drastically easier). Digdogger is especially annoying because you can only hurt it by using the Magnetic Gloves to pull a spiked ball into it—and towards you, and yes, it will hurt you if you don't let go in time—and Manhandla, a four-headed Piranha Plant that you have to fight with the Magic Boomerang, the most frustrating item ever implemented in the series.
Molgera. You have to get up really close to grab his tongue with the hookshot, but get even an inch closer than you need to and he'll eat you. It's nearly impossible to L-target the tongue after the first time, because mini-Molgeras spawn and get in the way, and it's even harder to target it manually because they'll hit you and interrupt your careful hookshot maneuvering.
Puppet Ganon, since you have to fight him 3 times, with him changing his pattern each time! Especially with the fast third form, an expy of Moldorm from A Link to the Past, where you have to hit it's tail with magic-depleting Light Arrows without the luxury of L-targeting. And especially the third form. Shoot a Light Arrow at the blue ball? Fine. Shoot a Light Arrow at the blue ball on the tail of a fast-moving snake that goes all over the place and never holds still? Better to shoot the guy who designed that phase. Performing an attack at Puppet Ganon's head immobilizes it, but you'll need quick fingers to exploit the narrow gap of opportunity. Those who are patient can jam themselves onto a ledge in the room where the Snake often can't touch Link. The trade-off is the tail becomes more difficult to hit.
The second battle with Phantom Ganon can last forever if the player doesn't figure out the riddle that holds the key to his defeat. Even finding the boss can be a bit tricky, since it requires the player to do something that completely defies previous game logic - yes, you have to jump off the ledge into that gaping, dark abyss, Hero.
The Legend of Zelda: The Minish Cap has the Giant Octorock. The main method of defeating it is to light its tail on fire with courtesy of the light coming from your lamp, but despite the thing's size it's incredibly fast and will often pull a 180 on you before you can completely get behind it. It doesn't help that you spend much of the fight on an icy floor, which means it's nearly impossible to go the right way you want to half the time. And finally you need to stay close by the thing if you want to properly hit it, but this also gives it an easier chance of using its primary attack of sucking you up into its mouth on you. Even if it isn't using the suck attack you'll still automatically be swallowed if you're remotely near it, which can lead to your health being depleted very quickly.
Twilit Bloat, aka the Giant Lightning Bug From Nowhere. You have to fight it on a ring of small platforms, it has a charge attack, and you have to jump on it and bite it to death. If you miss, it gets a free hit. Also, you're essentially helpless in the water, and when it does its rampage attack, the only way to be safe is if you have the agility of a cat on speed. The boss is especially hard if you don't realize you have to use the force field to target and hit all the legs at once.
The second difficult miniboss is the Darkhammer from the Snowpeak Ruins. He wields the Ball and Chain (which is the item you get for defeating him) and is fought in a narrow hallway which makes it very difficult to avoid. He is also only possible to harm from behind, meaning you have to wait for him to attack, clawshot your way across the room so that you are behind him, and then drop and hammer him before he turns around. That said, he is also the only boss or mini-boss in the game to lack Contractual Boss Immunity to the Mortal Draw. Seriously.
Fighting the Darknut for the first time can be this for those who aren't that great at the combat.
Argorok isn't particularly hard, but he's painfully slow to fight, especially in its second phase. If you fall, you have to spend at least fifteen seconds trying to climb back up to him. And you will definitely fall, especially when he starts randomly changing the direction of his fire breath.
The Roktites. A Giant Enemy Crab that waits on the roof of a tunnel and chases you through the mountain while you shoot its eye. After a while its eye only opens if you shoot an Explosive Barrel next to it, and finally it sends jumping minions after you as well. And it runs faster than your train, accompained by the nightmarish music that crescendoes as it gets closer.
Fraaz from the Blizzard temple for various reasons. His attacks are fairly tricky to avoid, and the ice/fire they leave behind then immediately have to be used against him with the boomerang once he switches elements. For extra fun, later on in the fight the boomerang needs to hit him multiple times before he launches the next attack. You have to do this with a measly four, maybe five hearts.
Phytops from the Marine Temple is no joke either. Every time he recovers from a stun, he attacks with two tentacles in a rapid succession that is hard to dodge. In the second half, he also strikes with them during his normal attack pattern in a left-right-both combo that is equally hard to dodge and can easily throw you off the cliff, resulting in another half heart loss.
Skeldritch, the Sand Temple boss, can be a pain, especially due to the sheer longevity of his battle. The first phase consists of catching the boulders he shoots from his spine with the Sand Wand and manoeuvreing them onto catapults before launching them back. Sounds easy enough, but his last few vertebrae are only vulnerable from certain angles, and he continually escalates the speed and intensity of his attacks as the battle progresses. By the time you've reached the last two vertebrae, you'll constantly being floored by his rapid-fire boulder barrage before you can do anything useful, and if you do succeed in catching one, it would be crushed in short order by Skeldritch's next shot.
The final form of Malladus can be a royal pain in the ass if you haven't gotten the upgraded Spin Attack. Trying to defend Zelda and having one fireball hit her and then having her start the whole pattern over again can be rather annoying.
The first couple of fights against Demon Lord Ghirahim are really frustrating, because he can catch your sword strikes with near-perfect accuracy. He's supposed to be a Wakeup Call Boss that shows you that you can't just swing the sword around randomly and hope to win, but even when concentrating and misdirecting him, it's hard to land any hits at all. The fact that he does all this with one hand, lazily catching your sword between two fingers, just makes it more aggravating, as it's clear he's just toying with you.
The second battle against the Imprisoned. The difficulty in this battle is upped considerably from the first fight, as the Imprisoned creates shockwaves with every stomp of its massive feet, making it impossible to come near it and Attack Its Weak Point unless you get really lucky with shield bashes. For people who simply jumped on his head he'll also throw you off after about a second. You're supposed to wait until Groose loads his catapult and stun the Imprisoned with that, but the downside is that this is a Timed Mission; you have to stop the Imprisoned from reaching the temple at the top of the map. In this battle, the boss can grab hold of a ledge and pull itself up, skipping a considerable portion of the map. You can slash his fingers when he's holding on but if you're way out of position you're stuck using the Groosenator. Which takes him roughly a minute to load after each use. It's not uncommon for a player to stun the Imprisoned with the catapult to land a few hits in, and while Groose is reloading have the boss pull itself higher. And if you save Groose for the times when the Imprisoned pulls itself up? Yeah, good luck approaching the boss with those shockwaves everywhere.
The third fight the Imprisoned is more of the same, up until the spike is driven in. From there on out, it's all the player's aiming skill with the Groosenator, and you can't afford to miss. The first time, it's not so bad, as it's a bomb and those can hit anywhere (but if you miss, consider reloading your save file - the Imprisoned is flying). It's the final shot that's the clincher - you have to aim at the narrow traversable ground on the Imprisoned's head, especially near the spike, and that leaves little room for error. If you aim too low, Link falls, and with the geyser it's not going to be enough time before the rails are crushed and the Imprisoned begins its attack on the Sealed Temple. If you aim too high or too far to the side, it will be almost impossible to make it back in time (there's the central geyser that hops Link back to top, but the time window to use it allows no mistakes at all).
When exploring Skyview Temple for the second time, players will encounter three Stalfos in what was previously the boss room. Later in the game this encounter would be child's play, but this is the first time the game throws so many enemies that require dextrous swordplay at the same time. Considering this is after the third dungeon, when there are still many Heart Containers to be collected, and that Stalfos can knock off multiple hearts with one swing, it's not a pretty fight.
And in the "Ancient Cistern", you'll have to fight Stalmaster, who's essentially one huge Stalfos with four arms, four swords, and a ton of health. You have to pretty much be a swordplay god at this point in the game.
In the last dungeon, you'll have to take on a trio of Stalfos again while a dozen Bokoblins on nearby ledges turn you into a flaming pincushion with their fire arrows. And right before that, you must somehow get past two giant Moblins on a narrow walkway. Both Moblins have unbreakable shields that are as wide as the walkway; hitting the Moblins with your sword is nearly impossible. You could use arrows to kill them, but this only works if you have lots of arrows (you can't leave the room to go get some), and afterward you won't have anything with which to shoot down those archer Bokoblins in the next room. And even if you survive all of this, A Stalmaster (formerly the miniboss of the Ancient Cistern) will await you at the end.
Scervo, the ridiculously frustrating miniboss of the Sandship. No Ring-Out Boss should ever have that much knockback. The fight takes place in a narrow, fenced-in "plank", so there's only one direction you can drive him out. And he's fast. He will hit you. A lot. It takes a second or two for Link to recover from the force and run back in, giving Scervo the chance to close the distance. And it's not enough when you finally manage to get him to the edge; you have to do it three times.
The final fight with Demise is exceptionally annoying. First, you have to hit him endless times avoiding his quick attacks, and if you get too far from him he just runs towards you, slashing you with his sword. Once you finally manage to make him fall to the ground, he gets up again, summons a STORM and charges his sword with lightning. Now you'll have to avoid both his skyward strikes and his regular attacks, exposing yourself every time you charge your own skyward strike, which is the only effective way you can stun him. Once you have managed to make him fall once again, you'll have to repeat the same process at least once more, and finally deliver the final blow. Oh, and make sure you're quick enough, because he'll get up right at the last moment. Have fun.
Zaganaga, the boss of the Desert Palace, is a tremendous pain. The arena is one big quicksand trap with small pillars that you can stand on dotted throughout it; the boss pops out of these pillars at random, and you have to use the Sand Rod to raise temporary platforms so you can get close enough to hurt him. Thing is, the temporary nature of said platforms means you may or may not have enough time to run all the way up to Zaganaga and slash him, and the whole time he spits out dozens of Peahats that fly into you and knock you into the quicksand. Making matters worse are the long-range beam attack he gains after he Turns Red, and the fact that he seems to have a lot more health than other bosses. At least the Sand Rod can be upgraded to the Nice Sand Rod so that the platforms it creates don't disappear, but it's not going to help too much with the Peahats and beam attack if you're not fast enough.
Knucklemaster replaces Mothula as the boss of Skull Woods, and it's no less aggravating. Its punch attack is very difficult to dodge, and requires quickly merging into a wall to avoid so it can crash into a wall and be vulnerable. Damage it more, and it gains a slamming attack that's also difficult to dodge, and destroys the ground you fight on, making it even harder to avoid its attacks. When it Turns Red, things go downhill fast. Its slams are faster, most of the walking space will be destroyed at this point, and every time it's left vulnerable, you'll get maybe three hits in before it starts attacking again. It can be skipped, but unless you've got a specific item to dodge its attacks, good luck.
Dharkstare, the boss of the Ice Ruins, is also a pain. First off, the arena is an icy surface, which means you'll slip all over the place, and is surrounded by a Bottomless Pit, and there's also a pit in the middle as well. Dharkstare never holds still, making it extremely difficult to melt its ice shield off with the Fire Rod, and it attacks by sending three energy balls out around your position in a triangular shape which after a few seconds freezes the area inside it. Unless you're already moving when it sends the triangle out, good luck not getting frozen. Oh, and when it Turns Red, it starts sending out a second triangle.
The Legend of Zelda: Tri Force Heroes is designed around three individual Links sharing the board. Henceforth, levels and especially bosses often require very efficient co-operation between players (which is difficult online due to lack of voice chat and emotes not being able to communicate certain actions), or in single-player careful placement of Doppels and switching control between them on the fly. To be specific:
Vulture Vizier is only a miniboss, but his battle is a nightmare. The arena is a large balancing platform with no guard rails, with the boss sitting on a perch off to the side. The idea is for one or two Links to stand on one side of the balancing platform, giving the third Link just enough elevation to attack the boss' face. The slightest off-balance nudge sends all three Links tumbling into a bottomless pit, resulting in three hearts lost with nothing you can do to prevent it. It's even more fun when the boss' attacks include pecking the platform to violently shake it, blowing gusts of air to blow the Links around and dropping statues to weigh the platform down.
Moldorm is back, and in single-player he's more annoying than ever. Moldorm homes in and chases the Link you're currently controlling, and he's pretty fast, very accurate and has a very big hurtbox (and, as usual, high knockback on an arena with no guard rails). You must carefully place a Doppel and lure Moldorm close to it, then very quickly switch control to attack Moldorm's tail. When you switch control to a Doppel, Moldorm changes his target very quickly, so you only have less than a second to attack. What's more, although Moldorm can't hurt inert Doppels, he can push them over the edge, so you have to keep them all near the center.
The Imprisoned is back with a vengeance. He has most of his abilities from Skyward Sword plus a few new ones, and is just as much of a pain to deal with here. His toes are still his weak point, so you have to be constantly putting yourself in range of his stomp shockwaves to hit him, the size and damage of which can get ridiculous when he's low on health. On harder maps he can deal huge amounts of damage, screwing the player out of an A-Rank with only two or three hits. His sheer size combined with the game's tendency to put him in small arenas makes him difficult to maneuver around, and he's been known to stand in doorways and block off entire portions of the map. He also automatically stands up when his weakness gauge depletes by half, preventing the player from breaking it in a single round (he's the only boss in the game who does this) and will immediately follow it up with his belly slide attack which renders him completely invincible until it's over, causing fights with him to take much longer than the other bosses. And a few sadistic maps will making you fight multiple Imprisoneds at once. One of the reasons the "Defeat 1000 enemies in 10 minutes" mission is so difficult is that it throws four of these guys at you at once, with no time to kill them, forcing the player to try and grab kills while running for their life from a bunch of hungry, angry Imprisoneds. Legends makes him easier to deal with by negating his automatic getup, and rendering him vulnerable to Focus Spirit Knockdowns.
The fight against Gohma in the Faron Woods level of story mode has the potential to be a pain. Gohma itself is actually not that difficult, as its only really notable attribute is that it's invincible most of the time and only opens up its weak point, its eye, after using its eye laser, which is pretty easy to dodge roll away from anyway. The problem comes from the fact that Gohma is primarily fought inside the Deku Tree base; your home base for the level, which will cause a game over if you lose control of it. Even this isn't so bad; where the problem really comes in is actually your allies for the mission. Gohma is shielded most of the time and can only be stunned and made vulnerable by shooting it in the eye with an arrow; your allies do not realize this and will simply crowd around Gohma and allow it to beat them to death without contributing anything else to the fight. This makes the fight a race against time to bring Gohma down before it kills enough of your soldiers to constitute losing control of the base.
Manhandla is also very annoying to fight. It's a simple process: stun all four heads with the boomerang (though the game may let you away with three or two stunned heads), and whale on the crystal in it's body. The issue here is that one of Manhandla's attacks is to rain hell on you. It's multi-hit, and if you aren't blocking, it will stunlock you, reducing a full life meter to zero in seconds. The worst part is that it looks similar to another one of it's attacks, namely, the one where it opens itself up for an easy quadruple stun. So more often than not, you may throw your boomerang, and leave yourself open to the seedling gun attack.
The final fight against Volga, as he's been powered up by Cia to tremendous degrees, meaning he can kill you very quickly if you're not careful. You aren't actually supposed to fight him in this state, instead waiting for Zelda (or Ruto if you're playing as Zelda) to talk him into rejecting Cia's power before you can take him down, but this takes about a minute to complete, which is more than enough time for him to finish you off.
Volga in every instance is a brutal struggle, considering that he's the Zelda version of Lu Bu. He's fast, hits very hard with combos that are hard to break out of if he traps you in them, can turn into an invincible dragon for good measure, his weakness gauge pops up for about half a second at a time and it only appears after attacks that are difficult to dodge whilst still being close enough to attack afterwards, hardly uses the attacks that do cause the weakness gauge to appear, and he takes an absolute ton of hits to defeat.note One saving grace, however, is that when Volga is hit while his Weak Point Gauge is up, it won't disappear for a few seconds, giving you enough time to drain it.
The fight against Cia is also a pain. The first portion of it is very easy, as she's just a regular humanoid enemy and can be knocked around accordingly, plus most of her attacks are very slow and require her to charge up power before she can even use them, which you can easily interrupt. The problem comes in the second portion, where she splits herself into four, and all four of them will often be on different places in her attack pattern, meaning you don't have time to stop all of their charge-up attacks. They also have a tendency of clustering together, meaning it's very difficult to get to one of the clones' whose weak point is showing without getting hit by the AOE attack of one of the others.
Phantom Ganon, introduced in Legends, can be an absolute nightmare. The first phase of Tennis Boss is fairly tolerable, but it's his second phase that makes the difficulty skyrocket: he pulls out a second sword, and foregoes the Tennis Boss pattern to ravaging your warriors with hard strikes that can break your block and send you flying. Plus, he doesn't appear to have any surefire way to expose his Weak Point Gauge, so all you can do is try everything until something works.note The secret is actually to wail on him from behind until he staggers, but this is in no way obvious. But it's almost certain to deplete a considerable portion of your character's HP before then.
Woe betide any fool who thinks Breath of the Wild is going to be an easy ride. If the Decayed Guardians and Guardian Stalkers that can sprinkle Link across the Hyrulean landscape with their lasers, and the Lynels that know no shortage of ways to butcher the Champion of Hyrule, do not drive this point home, then count on these bosses to etch the point into your flesh.
Thunderblight Ganon, the boss assigned to Divine Beast Vah Naboris, is the boss that fights most like Link, and thus the boss that will make his life most miserable. Phase 1 has it throwing balls like it has a Thunderbolt Rod when it's not flash-stepping into Link's face to carve him up, leaving you a scant second to react for a Flurry; the boss' shield will chew at any small arms' durability, making a heavy weapon ideal... but only for so long. Phase 2 has it bring out the lightning, dropping rods that attract thunderbolts to fry Link if he's in range, and its sword and shield are now electrified, meaning Link will drop all metallic equipment he's holding when contact is made. Take this boss lightly, and Urbosa will be waiting for you...
Aonuma said that you can face Calamity Ganon pretty much right away, but there is a vast difference between when you can face the beast and when you should. This thing has a wide variety of attacks, from Fireblight Ganon's blazing sword to Windblight Ganon's wind cannon to Waterblight Ganon's lance launcher, this thing copies a number of attacks, but its two unique abilities are what set it apart. First is its repulsor field; while this does no damage, if you're targeting the boss when it hits you, you lose a charge of Daruk's Protection, something this move appears made to do, and those charges are better used covering for you against an actual attack. Second, and more troublesome, is when it literally Turns Red via protective forcefield; this barrier protects it from all of your attacks, and only drops during its own attacks, leaving almost no blind spot. If you cannot Perfect Dodge or parry shots with your shield, this battle is unwinnable. Oh, and Calamity Ganon is preceded by every Blight Ganon you did not kill, including the aforementioned Thunderblight Ganon, meaning you've got a gauntlet from hell to go through if you choose to fight this thing straight away. Charging Ganon with the four Divine Beasts on the loose is a masochist's delight. You Have Been Warned.
The illusionary realm rematches introduced in The Champion's Ballad generally keeps the difficulty of the Blight Ganons the same as they were the first time they are fought apart from reducing the inventory to some early healing items, the Champions weapons and a few backups; the exception is Waterblight Ganon. The battle only gives you ten arrows, which is not enough to kill him in the second phase where arrows are the best form of offence. This reduces the battle to using bombs (which requires getting close enough that there is little to no time to stop Waterblight Ganon's Cryonis attack and do Scratch Damage anyway), using Stasis to knock an ice block back at him (which costs durability in a battle with limited weapons) or good use of Perfect Guard, Daruk's Protection and Urbosa's Fury.