Tabuu

Tabuu is the final boss of the Subspace Emissary mode of Super Smash Bros. Brawl. He has a transparent humanoid figure, with a pair of red eyes and a strange object inside of him. He is the "embodiment of Subspace" and created the Subspace Army. His name is a corruption of the word "taboo", which means unacceptable or improper by society's terms. The spelling of his name is derived from a katakana transcription of the word, romanized for English language releases.

Background
Tabuu is the embodiment of Subspace. Observing the World of Trophies, he has the desire to cut the world into pieces and bring it into Subspace. However, because he cannot leave Subspace, he is forced to form an army in order to do this. After studying the world and its inhabitants, Tabuu takes control of Master Hand, the master of the world, and using Master Hand recruits Bowser, Wario, and Ganondorf. He also notes the peculiar structure of Mr. Game & Watch, and uses him to create Shadow Bugs, which form the soldiers for the Subspace Army.

Tabuu also takes notice of Meta Knight's ship, the Halberd, to use as transportation for his army, and is successfully able to attack and capture the ship. In addition, he learns of the advanced technology on the Isle of Ancients and conquers the island, using the Robots to build weapons such as Subspace Bombs in order to take parts of the world into Subspace, the Master Robot joining him in the process, turning into the Ancient Minister, serving as a deployer for the immensely powerful Subspace Bombs.

The Subspace Emissary (Super Smash Bros. Brawl)
After suffering a humiliating defeat, Ganondorf and Bowser enter Subspace to seek out Master Hand. Planning to take control of the army, Ganondorf betrays Bowser before approaching Master Hand and bowing before him. Just as Ganondorf prepares to attack Master Hand, Tabuu reveals himself. Ganondorf tries to free Master Hand by attacking Tabuu, but he easily overpowers Ganondorf, turning him into a trophy with a single attack. Ganondorf falls on Master Hand with enough force to sever Tabuu's strings of light, freeing Master Hand. The weakened Master Hand attempts to destroy Tabuu, but Tabuu easily reflects his attack, stunning Master Hand.

The heroes later arrive and confront Tabuu, who spreads his wings and releases his ultimate attack, the Off Waves, instantly transforming every fighter to their trophy form. He then puts the pieces of the world taken from the World of Trophies to create The Great Maze. However, Luigi, King Dedede, and Ness return back to their original states thanks to the brooches Dedede had invented. The three travel to Subspace and return the heroes to their original forms.

After making their way through the Great Maze, the heroes arrive at Tabuu's lair for the final showdown. Tabuu prepares to use his Off Waves again, but Sonic the Hedgehog appears and attacks Tabuu, shattering his wings and preventing him from transforming the group into trophies. The heroes then face Tabuu in the final battle. After he is defeated all the pieces of the world taken into subspace and all the characters are returned to their proper locations.

Super Smash Bros. Ultimate
Tabuu is set to appear as a spirit in Super Smash Bros. Ultimate.

Attacks

 * Off Waves: During this attack, Tabuu appears in the background and opens up his wings which proceeds to release three red shock waves. These shock waves deal very high damage and knockback, enough to one-hit KO on normal and higher difficulties in SSE and on very hard and intense difficulties of Boss Battles. To avoid the shock waves, a character must either roll or sidestep dodge with accurate timing. If playing as Pokémon Trainer, Kirby, or Zelda/Sheik, using Down B the instant Tabuu extends his wings also works. The player can also Perfect Shield, despite the fact that the attack is unblockable. The effects of a Metal Box will help resist this attack, in which case, the character is only slightly pushed.
 * : Tabuu appears on one side of the stage and takes out a large, dragon-shaped cannon, which fires a powerful laser that can only be dodged with a jump.
 * : Tabuu transforms into a wide spear and attacks sideways with one swipe.
 * Chain of Light: Tabuu takes out a gold chain, grabs the character, swings them around and slams them onto the ground for high knockback. This move uses the same type of chain that he used on Master Hand.
 * : Tabuu transforms into a giant version of himself and appears on either the left or right side of the stage, before unleashing red lasers from both his eyes. They mostly work the same way as Master Hand's lasers, including leaving their user vulnerable to attacks, but Tabuu's lasers are significantly more powerful, and are different in that they only take effect at the point of contact with the stage. They can be avoided by running to the edge of the stage where Tabuu is located.
 * : Tabuu appears in mid-air on one side of the stage and attacks the stage with a curved swipe of a red energy sword. It is avoided by jumping.
 * : Tabuu teleports around the area and appears at a set spawn position which is randomly decided from the large amount of spawn points available. He also sometimes teleports behind the character and attacks.
 * : Same as his normal teleportation move, but it creates a red explosion everywhere he teleports.
 * : Tabuu teleports to a random area and releases energy from the object inside him to circle around him like a shield and attack.
 * : Tabuu teleports behind the character and rapidly slashes the area near the character. The attack has less range than the visible shockwaves would indicate.
 * : Tabuu transforms into two brackets and flies across the stage, grabbing the character (if he's not avoided) and slamming them onto the stage. On Intense difficulty, this attack is a one-hit KO.
 * : Tabuu points at five locations which will blink. Those locations will explode after a second, damaging anyone who did not move away in time.
 * : Tabuu appears in a random area in the air and fires a series of small, magical bullets. Tabuu concludes this attack with a powerful energy blast, all of which is avoided by staying behind him.
 * : Tabuu appears on one side of the stage and throws a round boomerang which crosses the stage twice before he catches it. This is avoided by jumping and using Up-B (depending on character) to avoid the second swing.
 * : Tabuu pauses in midair and sends out copies of himself in all directions. Characters will take damage if they make contact with a projection.

Trophy information
The Tabuu trophy is earned by use of a Trophy Stand. To get the Tabuu (Wings) trophy, the player must clear the Boss Battles game mode with every playable character.

Trivia

 * Tabuu's moveset is very similar to Marx's moveset from Kirby Super Star.