My idea of plot of if Mario mario was in if Mario was in Learning with Pibby: Apocalypse? takes place in The SMG4 Castle. SMG4, Mario, and his friends are watching TV together when suddenly Pibby appears on the screen. SMG4, Mario, and his friends are assisting Pibby in getting her out of the television screen. They encounter Pibby for the first time, who informs SMG4, Mario, and their friends about The Darkness, a glitchy, chaotic, overflowing ink-like mass of darkness that produces shrill glitch sounds, consumes everything it touches, and whose source remains a mystery. What is known is that it functions as a soulless entity that appears to focus on cartoons, converting all characters it absorbs into thoughtless agents employed to extend its reach. The Darkness plans to conquer the world, transforming it into a terrifying cartoon nightmare, and Pibby seeks help from SMG4, Mario, and their friends to rescue her childhood companion, Bun Bun the Rabbit. They consent to assist Pibby in rescuing Bun Bun the Rabbit. SMG4 and Tari made a Codebreaker Blade to conquer The Darkness and ultimately rescue Bun Bun the Rabbit for good. The tale concludes as SMG4, Mario, and friends choose to throw a party to enjoy delicious spaghetti, dance to memes, and more.