Okay for my BnHA x Pokémon au there will be fan made variations of pokémon. For some examples Dabi will have an Obsidian! Charizard (like shiny Charizard but charmander and charmeleon are also black and Charizard's wings shift from blue to purple depending on the lighting)

Geten will have a frostbiten/black ice Glaceon where it's just black, grey, and white. Also the diamond pattern on Glaceon will shift into black/grey/white snowflakes.

Also Eri's shiny Celebi hateched from an egg and no one knows why

I'm not sure if other people are getting special types of pokémon but will update this thread when more ideas pop up