Super Smash Bros. Great Fray was notable for having more bosses than even Super Smash Bros. for 3DS/Wii U or even Super Smash Bros. Brawl, as well as more enemies than the mentioned games. Most enemies are even weaker compared to Super Smash Bros. for 3DS's Smash Run and strong enemies will side with the player shall he/she make enough damage on that enemy.
Bosses had categorized into three types; Stage Bosses, Assist Bosses and Boss Fighters.
Stage Bosses: Traditional bosses that appears only in specific stages. Unlike in other Super Smash Bros. games, he/she/they will only appear if the respective stage is turned into Boss Version.
Assist Bosses: Summoned from Assist Trophy or Poke Ball, it will help the summoner to defeat the opponents, but will sides with the attacker shall the latter one deliver enough damage. Unlike regular assistants and Pokemon, Assist Bosses will only stay until he/she got defeated.
Boss Fighters: Substitute the breaker of the seal until he/she got defeated. They are considerably more mobile than most Assist Bosses does to being able to do everything a normal Fighter can do, including Final Smashes and Great Fray. They can also be played by holding the L button for two seconds to make the Boss Fighters selection during the Character Selection, although they cannot be played in With Anyone in Online Smash. They can also be customized from the Customize when also selecting a character, and all of their Custom Moves for their default and alternate Special Moves are unlocked at the start.
The Legend of Zelda
The "Mastermind of Masters", Master Hand is more than just a floating hand; it is said that he created the Smash universe (and possibly beyond), and after discovering mysterious energy he called it the Smash Spheres, he and Crazy Hand become intensively powerful, to the point that even Tabuu will not be able to control him anymore. He is the wiser but stricter of the two Smash Hands.
His new attacks include Judgement Punch, which temporily disable Special Moves, and Space Manipulation, which as the name implies, manipulate either the platform itself.
Final Destination or Fatal Confrontation
The "Cutthroat Clown", Crazy Hand is the opposite of Master Hand; aside of being literally left-handed, Crazy Hand will destroy anything that is deemed too dangerous or too lame (thankfully he never do it on people as doing so is "beyond his standard"), but he also sneakier and more sinister, but also more excited and a big sense of freedom, which causes the two Hands to fight at each others shall one of them went too far.
His new attacks are Oblivion Axe, which cause OHKO to anyone who have damage percentage at 100% or over, and Mini-Crazies, which he split into smaller Crazy Hands to dive into one of the fighters.
Final Destination or Fatal Confrontation
Master Hand's strongest form after Super Smash Hand, Master Core takes multiple forms and each of them are pretty terrifying and certainly not friendly. The forms are the following; Master Giant, Master Beast, Master Edges, Master Shadow and Master Fortress, and then his exposed Core at full end as well as two new forms;
Master Fighter: Master Core's fighting form, and replaces Master Shadow as of 7.5 Difficulty. Unlike Master Shadow, Master Fighter have an unique moveset and must be launched offscreen to defeat him.
Master Dragonoid: Master Core's dragon-esque form, hence the name. He breathes fire, but also unleash slashes, bites, and a powerful roar. Replaces Master Beast as of 8.5 Difficulty.
After all these years, Crazy Hand will show his own Core Form, and this one don't use Swarms, but instead elements, such as fire, earth, air and water. They certainly looked more terrifying does to their exposed details of demonic monsters! The forms are Crazy Eruption, Crazy Hurricane, Crazy Earthquake, Crazy Sprout, Crazy Army, Crazy Fighter and Crazy Sunstrike. Shall you waste time on his exposed form where you should finish him, he will absorb you and then spit you so hard that you launched away off the screen!
One of Bowser's elites in Super Mario 3D World, and unify his blobs into one big, clownish, blob monster. He'll uses diverse attacks using his blobs, but a big stomp will cause the blobs to split, which leave him vulnerable!
Super Mario 3D World
The Koopa Clown Car is left unintended... this means that any players can control it! That's right, the player can hop on it and gain the high hand in order to overwhelm the foes. There are classics attacks like throwing Mecha-Koopas and slamming down the floor, as well as spinning ahead, but getting it blown up from too many damage and up to the sky!
The Strength Pokemon. Its strength is unlimited, and nothing in everywhere will scratch its armor easily! That being said, it only have few ranged attacks, such as Earthquake, but all of its attacks are painful to take. It is also slow most of the time, but it will use Mach Punch shall you get too distant from that.
Ironeo Battle Tower
The Spirit Pokemon. That mechanical being doesn't looks like a Pokemon nor an Ultra Beast, but it is the former case. In fact, it is designed to be more powerful than Mewtwo, and it sure shows. Unlike its rival Toughust, it is more about Special Attack and is much faster, but isn't as capable to take as much damage as its rival is able to.
Ironeo Battle Tower
King Zing is one tough king of Zingers (although in real life, there is no such "king bees", only queen bees). Just touching him will hurts, and he is surprisingly resilient. His weakness is his stinger, but he also uses it for attacks, so hit it when he doesn't use it. Once he had taken enough damage, he will shrink and summon the Zingers to put you down!
Chorttlebot is one of the bosses Wario faced in Wario Land: Shake It!. It cannot be directly damaged with any attacks on anything but its bottom where his weak spot is. This is not easy, as it is a bit agitated so damage it with its own bomb to immobolize it.
An ancient weapon seemingly revived by Andross. That... being... made of bones is scary, and you have to break his to attacking appendages to break it and leave the chest open, revealing its weak spot. That being said, he will also attempt to swing his tail and other wild attack to stomp the fighters.
Saturos and Menardi are the dual antagonist of Golden Sun, and the most well known of the Golden Sun series' villains. Each had their own arsenal, which is dangerous for those who are not familiar with the whole series. And as if this is not bad enough, they will eventually fuse together into a Fusion Dragon when taken enough damage! Talk about a bunch of evil beings!
He may look like your typical bird villain, but you wouldn't know until now that he is much taller than Captain Toad and Toadette. How tall? Here's a clue; he's a giant crow! He uses various kind of magic in order to dispatch the fighters, but he becomes vulnerable when you throw a Vegetable back at him.
Yuga-Ganon is a fusion of the sorcerer Yuga and, shockingly, the Demon King, Ganon himself. Now, the plot twist is that it is not Ganon who is possessing Yuga but the inverse! Yuga-Ganon uses various dark magic to defeat the fighters, and will flat himself on the wall like a paint portrait in order to evade from the fighters and also to pull a sudden strike.
When a final boss piloted machine is capable to infuriate you the first time you faced it until you know the trick, you know that Dr. Eggman isn't fooling around. The Death Egg Robot is introduced in the Sega Genesis' Sonic the Hedgehog 2, and a tough one at that. While he had only one arsenal to protect his back, all of his other attacks are burtal and can defeat a fighter in one or two hits! Even the Smash Hands warns you to not foolishly take on that deadly machine!
While the Death Egg Robot may be Dr. Eggman's favorite "final boss machine", the Big Arm is not a pushover either. Especially when it is actually capable to catch Super Sonic and slam him to lose his rings! (Not in this game, thankfully.) Attack on his back, and unlike the Death Egg Robot, Dr. Eggman's only way to attack someone behind him is to turn around!
Guts Man G is a deadly machine. Yes, there is a Guts Tank before this upgrade, but the Guts Man G is actually the real Guts Man (or a replica) himself! Rushing at him is a bad idea, as he will catch you and throw you up to the upper screen limit, which means that you had to strike wisely.
Wily Castle 7
Dr. Wily himself had finally show up in Super Smash Bros. as a boss... in his Wily Machine No.7. Although the first phrase is a cakewalk when you know the pattern, its the second phrase that would make you throw your controller out of frustration. Thankfully, the dodge mechanic is your saving grace, but you still need good timing in order to dodge his tricky orbs!
Wily Castle 7
One of the big bad bosses Mario had faced. Introduced in Super Mario Sunshine, Petey Piranha is a powerful, beastly plant, and is also stronger than even Bowser or Ganondorf (in term of strength for the latter one). Watch out for his goop attacks!
Flower Beast Petey becomes much stronger, and his inky attacks had extended range. He is also more heavy, so racking him damages first is a wiser choice.
One of the recurring The Legend of Zelda bosses, and had a thick and tough armor that most attacks cannot go through. Queen Gohma is fairly quick, and her shield is among the most durable, even when compared to Porky's. However, she takes more damage when getting hit on her eye.
Fierce Armor Queen Gohma's armor is so solid and thick that she never flinches until she reaches 100%. She also becomes faster, but also fall a bit faster.
A tough leader who do really living up with being King of the Snowmads. He uses his horn to spit out icy spikes, and he the second fastest but also the most agile, which make him a truly brutal walrus! Brace yourself when he is coming through!
Ice Dragon Master He enlarge himself and his horn as well as able to enhance his Special Move in a phenomenal way. For instance, whatever his Neutral Special Move is, he also fires an Ice Dragon out of his horn! Freezing!
How could Groudon be in!? Well, that role would live up against its absence in Super Smash Bros. for 3DS/Wii U. Being the absolute heaviest Boss Fighter of them all (a mindblowing damage percentage of 150% is best to get rid of that monstrous Pokemon!) and just one forward Smash is slow but a guaranteed knockout to even the other Boss Fighters...except of another Groudon!
Primal Groudon Groudon grabs its Red Orb, which Primal Reverse it into Primal Groudon, a bigger, heavier and obviously more powerful. This will take 200% this time for a real K.O. against that beast! Oh, and its Special Moves are more powerful, too.
The Legendary Pokemon that represent the Moon. With its unlimited flight and highest air speed, it will recover like no problems, and its Special Move are very dangerous, so be prepared to take on this somewhat elegant but deadly Pokemon. Just hope that the power of the Moon will not make you asleep!
Ridley is too big to be a Boss Fighter? Don't get started with that. Anyway. Ridley is the fastest in term of ground speed, but is more skilled in aerial battle than on ground battle. He is a bit more of a Light-Weighted compared to the other Boss Fighters, but his agility can make him a merciless foe to anyone on his way.
Meta-Ridley The even more vicious version of Ridley. Stronger and more resistant, Meta-Ridley becomes a nightmare machine, although this also limit his ground capacity very much.
Apparently, the Smash Energy had somehow allowed him to get up. That's right, its King Hippo, one of the most iconic opponents of the Punch-Out series. He is surprisingly the second most heaviest Boss Fighter (next is the Heaviest Pokemon of all seven Game Freak generations, Groudon) and have a dangeous amount of Super Armor. Too bad that he fall fast. Unfortunately for you, he cannot be grabbed until he reaches 100%.
Fruit Frenzy Hippo He eat a lot of fruits! This not only heal half of his damage (which suggest you to hurry up and not letting this from happening) and his speed and attack are greatly boosted. If he catches you, please never let him break your shield!
Ness' naughty neighbor yesterday, omnicidal tyrant today. His robotic mech takes less damage than the others, but his attacks can be easily avoided if you know how his attacks works. His shield is as durable as Queen Gohma's, and his Porky-Bombs can hurt anyone, including himself.
Demonic Spider Mech Porky's mech becomes even more spider-like, and his Special Moves are even more performant, as well as more launching reisstance. The problem is, now that he got exposed, he could also receive even more damage shall Porky himself get hit!
This is the most despicable Mechon you will ever meet! In a good way, of course. Tied with Medusa, he may be the tallest Boss Fighter (slightly more than the towering Primal Groudon, the Great Fray of Groudon itself) and thus have greatest range but also easiest to hit, but he also never flinches from standard attacks and weak Special Moves, forcing you to knock him over with clever Aerial Attack assaults.
Black Face He is now more mobile and more dangerous, and his technical Special Moves can causes more destruction to everyone and himself alike! Don't get too reckless when using him!
Queen of the Underworld. Just like Metal Face, she is the tallest Boss Fighter, although she rely more on her Special Moves than Metal Face's brutal claws and mechanism. This could want her to take distance from you, but thankfully, she is one of the lightest weighted Boss Fighters! Just don't let her petrify you!
True Medusa This is her true form...and a terrifying one at that. Her Special Moves are more trickier, without mentioning her more damaging Smash Attacks. However, she is also more light-weighted, even a bit more than Marx, so maneuver when playing as her.
One of the almighty final bosses from the Kirby series. Marx is the one who deceived Kirby by pushing out of his way and demend the Galactic Nova, as a wish, to conquer Pop Star. This troublemaker becomes even more troublesome, with rapid Super Smash charges, even more unpredictable actions, and medium weight despite being smaller than the others, and yet he also have the greatest range!
Marx is unlocked once he or Marx Soul is defeated in Vs. Marx as the Final Battle of City Trial in Smash Run.
Marx Soul The crazed and insanely powerful version of Marx. He is faster, stronger, and take less damage, but his launch resistance does not changes. Worse still, he could even stay like this for longer every time he had successfully taunted! What a tormentor!
One of Master/Crazy Core's forms during the battle. They replaces Master Shadow and Crazy Army during their respective battle. They do look identical, we agreed, but they are also large, imposing, agile, powerful and resistant, but also have a weakness (the Core itself) which takes more damage and launching vulnerability (and even more when dizzy).
They become unlocked once you defeat Classic Mode from 7.0 to 9.0 difficulty.
Super Smash Hand The ultimate form of Master Hand/Crazy Hand, combining his Hand and Core form. This extreme Hand version is more powerful, more agile and constantly float instead of falling! The true way to get rid of them is to rack them up damage, and then wait for them to attack, dodge and unleash your powerful attack! Their attacks are also greatly different from their Master/Crazy Fighter counterpart, so you need practice on using this Great Fray.
Bosses' Threat Level
This demonstrate if the Boss is as threatening as it looks or actually not too much of a threat. The bosses are tiered based on exactly how dangerous are they and other aspects, such as how many damage it will take in general before being launched off screen in Final Destination or if it is a Stage Boss, on their own stage. From top to bottom, Terrifying is the most dangerous, while Threatening is the least.
This version is the widely accepted one by the Smash community, under condition of using only default moves and no equipment (or Custom Orbs for the Assist and Stage Bosses' case), as well as tested with every fighter available, including Boss Fighters themselves, to determinate how exactly dreaded the specific Boss Fighter is. In Marx and Master/Crazy Fighter's case, they were difficult to unlock and as such as the Threat Level is revealed, mod-authorized players will test them in order to be sure, before finally given a respective level at several weeks later.
The current most dangerous Boss Fighter is Master Fighter (and its palette swap Crazy Fighter), does to their high overall stats such as strength and weight, as well as powerful and versatile Special Moves. The second most dangerous is Groudon does to his huge weight and launch resistance, enormous physical power and strong Special Moves.