YMMV / MarioFan's What If?

• Complete Monster (What If The Mario Brothers Were Imprisoned in Paintings?): King Boo, in this universe, is able to defeat Luigi at the end of Luigi's Mansion instead of being defeated by him. King Boo would first trap the Mario Brothers inside a painting, putting them in a Fate Worse than Death. King Boo declared the Mushroom Kingdom responsible for the "crimes" that the Mario Bros committed against the Boos and led an invasion that got a majority of the kingdom and his own forces killed. King Boo later murders Princess Peach when she calls him out on how his revenge quest is about him. King Boo then plans to invade every single kingdom that is allied with the Mushroom Kingdom, despite warnings that this will be a Suicide Mission. When the Boos try to overthrow King Boo, he declares them all traitors and attempts to kill them all.
• Magnificent Bastard (What If Fawful Absorbed The Dark Star?): Instead of partially absorbing the power of the Dark Star, Fawful learned enough to absorb it fully. Fawful first frees and grants Midbus a place by his side and power as a reward for his loyalty. Fawful brainwashes Bowser then has Bowser's minions take over the Mushroom Kingdom, then has them lead a false attack against the Beanbean Kingdom so that he can convince Peasley he is trying to help. At the same time, Fawful trapped the heroes inside the pipe system so they could not interfere. Fawful plays the Beanbean and Mushroom Kingdoms against each other to weaken both armies to conquer the world. When the heroes escape, Fawful stuns the Beanbean army, so they can't help. Fawful nearly wins and is only stopped by Starlow's Heroic Sacrifice.