Dimentio is a major antagonist in Super Smash Bros. Crossover during the Fourth Dimension Arc, and is ultimately the one who sets the arc into motion. Dimentio is also the only villain who accompanied Mechtavius Destroyer to the Fourth Dimension that apparently remained loyal to him, as Link and Zelda are operating under their own agenda. However, Dimentio later reveals he has his own motives, and desires the Dimensional Stars for his own purpose.
Prior to Season 31, Dimentio was a member of the League of Villains. Eventually, Dimentio learned about the Fourth Dimension, and sought to get there for his own plans. Tracking down the DBD of the main dimension, Dimentio travelled to Gundalia and began excavating for the DBD. During the heroes' battle against Mechtavius Destroyer, Dimentio is nearly hit by a stray blast, and rudely asks that the combatants watch where they fire. However, Dimentio then finds the DBD, only for it to be taken by Mechtavius Destroyer, who uses it to go to the Fourth Dimension, with Dimentio, Link, and Zelda tagging along. Upon arriving in the Fourth Dimension, Dimentio assisted Mechtavius Destroyer, Link, and Zelda against the Heroes of Legend, and was seen battling Zombie Iron Man before retreating with Coredegon. Dimentio later informs Coredegon that the Heroes of Legend have already acquired 5 Dimensional Stars, and suggests that they let the Heroes of Legend bring the D-Stars to them, which Coredegon agrees to, but insists that they still try to interfere to avoid suspicion.
Dimentio later confronts Gohan and Boo Rock at Blood Garden and, in an unexpected move, gives them Blood Garden's D-Stars, Bob-omberman's D-Stars, and even activates the Vanish Caps for them. Dimentio then heads to Hurl-Ya Harbor, and gives Goku the D-Stars of Hurl-Ya Harbor and the Metal Cap course, and activates the Metal Caps as well.
However, Dimentio's actions did not go unnoticed, as Coredegon later tricks him into giving Dowser's D-Stars to the Heroes of Legend as well as the key to the 4D Tower. Since he didn't hesitate, Dimentio unintentionally exposed his true colors, and is punished by Coredegon for his treason. Despite this, Dimentio manages to survive somehow, and reappears just before the Heroes of Legend prepare to face the Nomadic Mechtogan for the last time.
Dimentio reappears in Season 32 along with Zombie Reed, Fawful, Magolor, Black Doom, and Marx as part of a team created by Mechtavius Destroyer to instill chaos within the heroes and prepare the Earth for "the day of reckoning". Dimentio's reasons for working with Mechtavius Destroyer again are currently unknown.
- Dimentio is the first villain that isn't related to Coredegon in some way to work with him since The Grand Finale.
- Dimentio's motivations are the same as they were in Super Paper Mario.