Even notwithstanding all of the below (several enemies and other aspects of Mario 2 showed up in later Mario games, so we can only suppose its as “real” as any), Yoshi is also a strong contender for being trans. He is consistently referred to as male but cranks out eggs at an assembly-line pace and thus might be biologically female.

But then, so does Birdo. So who the hell knows how dinosaur-things work in Mario’s world.