keepitsimple, I know this doesn't seem like the greatest of ideas but I just wanted to see how this might go. Just like the one game about Pokemon but instead it's about characters a member might be buddies with! It can be range from TV shows, ads, books, comics, video games, the entire cornucopia! Just keep it to fictional characters such as generic enemies, main protagonists who have bland personalities but decent combat skills, Deadpool, Paul the three-eyed monkey, the General, etc (and yes even Pokemon characters haha)!
Just follow all SPPf rules and don't use actual people, dumb things like OCs from awful fanfiction/art, etc. Also list the origins of the character that you listed came from like this:
Mario (Super Mario)
Or some variation of it. As long as we know it's a legit fictional character!