It was really hard to make Star Platinum look like a Pokémon because… well… he could be one without any design changes! Especially ever since the likes of Buzzwole showed up. I couldn’t choose between Psychic or Ghost, but I think Physic fits better since a Stand is a manifestation of the mind.
Patrons can submit prompts for Fake Monday (and Tuesday Chooseday and the webcomic too, by the way) by commenting on the prompt-post I put up every Monday. So if you want to submit your ideas for fake Pokémon, become a Patron!