After Mario, Princess Peach, Bowser, and Luigi defeated Count Bleck, Dimentio brainwashed Luigi with a Floro Sprout, assumed control of the Chaos Heart, and combined with both into Super Dimentio, who resembled a giant cross between Luigi and Dimentio. Super Dimentio was invincible at first, but lost his invincibility when Tippi arrived with the revitalized Pure Hearts. Mario, Peach, and Bowser fought him and eventually defeated him. His body was destroyed, leaving only his head, near death; however, he left behind a shadow of his power to control the Chaos Heart and ensure the end of every world, before he exploded, sinking into the ground and obliteration, releasing Luigi and the Chaos Heart unharmed.
The Chaos Heart was later destroyed by Tippi and Bleck to save all worlds.
Super Dimentio has 200 HP, and an attack power of 6. His defense is 0, but his body's defense is 4. The platforms of the room now have Dimentio's face on it and are moving around. Super Dimentio has more physical abilities than magical. He can target the player and shoot square-shaped bullets at him/her. These move slowly and do 3 damage. Super Dimentio cannot be damaged when the battle begins. After he is attacked for a few times, however, Tippi will return with the Pure Hearts, and Super Dimentio can now take damage. Another of Super Dimentio's attacks is to use the Super Jump and jump high up. He will then come down, with a target symbol indicating where he will land, always trying to land on top of the player. The player can only control Mario, Peach, and Bowser. Bowser has twice Mario and Peach's attack power, and a ground pound with Thudley the Pixl does double damage, which makes Bowser and Thudley an effective combo against Super Dimentio, especially as it is easy to continue to stomp on his neck. Breathing fire is also effective if Super Dimentio's head is close. He is easier than Count Bleck.
- Super Dimentio is the equivalent of Dark Fawful combined with the Dark Star Core on Mario & Luigi: Bowser's Inside Story, as both are in a bigger form combined with an evil object, and the end result is the psychotic villain left as just a head, near death, and trying a last ditch attempt to take the main characters with him.
- Super Dimentio's theme song is a combination of Dimentio, Mr. L, and the Chaos Heart, and is called The Ultimate Show.
- Super Dimentio is the only final boss in Paper Mario whose theme song does not change after the intermission in which his invincibility is lost (as all three final bosses start the battle invincible, and a long scene commences in which the invincibility is countered).