June 7th, 2024

This adaptation takes place before "World of Light".

In this setting the Mayor from “Powerpuff Girls” (Mario) and Chowder face each other on a stadium and in the setting, when a fighter is defeated they become a trophy which can be revived by touching the base by an active fighter. Suddenly the Battleship Halberd appears and releases a stream of purple particles known as Shadow Bugs that form the soldiers of the Subspace Army. The Ancient Minister, the army's cloaked general, arrives and detonates a Subspace Bomb, which can only be detonated by the sacrifice of two ROB units (the aforementioned robot race is depicted in the art style of Futurama) and transports the stadium into Subspace, an alternate dimension where the Subspace Army resides. The Ancient Minister's advance prompts the fighters to join forces and attempt to repel the threat, while villainous fighters harvest the power of the allied fighters by using powerful weapons that instantly reduce them to their trophy forms and using the Shadow Bugs on some of them to create evil doppelgängers. Dee Dee (King Dedede) begins independently gathering some fallen fighters, placing golden brooches on them.

The Ancient Minister is revealed as a subordinate of Uncle Grandpa, Eduardo, Eddy (Wario), who are under orders from Master Hand to draw the world into Subspace. Eddy, who had kidnapped Steven Universe (Ness), is defeated by Chloe Park and Jimmy from “Ed, Eddy n Eddy” (Lucas), and his trophy form is then helplessly sucked into a Subspace Bomb's detonation. Meanwhile, Mandy from “The Grim Adventures of Billy & Mandy” (Meta Knight) leaves her group to reclaim the Halberd as he allies with Nicole and Hoss Delgado and neutralizes the source of the Shadow Bugs – Father from “Codename: Kids Next Door” (Mr. Game & Watch). The Ancient Minister's true identity is found to be Robot Jones (ROB) who rebels against Uncle Grandpa to join the fighters when the latter detonates several bombs on its home, the Isle of the Ancients, to create a rift into Subspace large enough to summon the Subspace Army's ultimate weapon – an enormous warship. The three major groups converge and use the Halberd to battle the ship.

Although the Halberd is destroyed, all of the characters escape unscathed and Uncle Grandpa and Eduardo retreat after Chowder destroys the ship with his Dragoon. After betraying Eduardo, Uncle Grandpa discovers that Master Hand was being controlled by the army's actual leader and the embodiment of Subspace, Tabuu, who defeats Uncle Grandpa and Master Hand. The fighters confront Tabuu, but the latter annihilates them all with a cataclysmic attack known as his "Off Waves" and scatters their trophy forms all throughout his dimension. Dedede's brooches are soon revealed to be a failsafe against Tabuu's Off Waves and revive Mung Daal (Luigi), Dee Dee, Steven, and Chowder, who rescue the fighters and navigate a gargantuan maze-like amalgamation of the areas that were transported into Subspace where Tabuu is located. As Tabuu is about to use his Off Waves to dispose of the fighters once and for all he is attacked by Gumball who weakens him; the fighters then defeat Tabuu and save the day. In the final scene, the fighters look at a great luminous cross on the horizon where the Isle of the Ancients once resided.