MarioUniverse is a doppelganger of Koopa created by Wikia with the intent of damaging Koopa's friendship with the other Rulers of Wiki by any means necessary. MarioUniverse bears a striking resemblance to Godman, just as how Koopa resembles Greenman. Unusually, MarioUniverse often bleeds from his eyes despite actually being a robot, for reasons unknown.
Prior to his battle with Koopa, MarioUniverse encountered Redman. Unable to use his mind-breaking abilities on Redman, MarioUniverse decided to fight the hero directly. Despite this, Redman triumphed over MarioUniverse, who reluctantly retreated.
The embodiment of Koopa's sadness and self-doubt, Wikia intended to create something Koopa could not defeat, and this was indeed the case. MarioUniverse's very presence emotionally weakened the Ruler of Wiki to a profound extent.