Stactus is an unreleased Pokemon seen in the manga "Satoshi Tajiri: The Man Who Created Pokémon". Looks like it'd have been an interesting Pokemon, though I suppose it didn't make a lot of sense as Kanto doesn't have any environments fitting for a cactus.

(Stactus is not an official name, it's just a name I've seen given to it, and it seemed fitting enough)