I don't think you understand just how complicated some of those scripts are. Like, Kirby? Copy who? Just co-op friends? You certainly can't copy all of Kirby's abilities. What would it do in single player then? Even inhaling/spitting would take a lot of work to implement, even if you got the creator's permission to use their script. Yoshi is a similar situation, as is the Enerbeam. They are REALLY complex, even if you just pick one of their functions. And of course, you'd need the creators' permission to use any of them. And as he stated, he doesn't want to use a lot of others' code either.