One imaginative Pokemon fan is designing Mega Evolutions for the Generation 1 creatures that currently dont have an official one, including the slimy Muk. This slimy Sludge Pokemon evolves from Grimer at level 38, and both of them could be found in the Pokemon Mansion on Cinnabar Island in the original Pokemon Red and Blue. They would then ooze their way through later Pokemon generations, even gaining colorful Dark/Poison Alolan variants in Pokemon Sun and Moon.