Ermagersh, productive conversation?
adding more costumes has already been handled by cBliss. The clone engine has to handle a LOT MORE than just managing costume flags and cosmetic textures

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Edit:
I might stream my screen and port a character from scratch sometime soon, would anyone find that interesting?
Yes, please. If it's possible, do you think it'd be possible to have a tutorial of sorts as an intro to this type of hacking?
I'm the type of person in that I'd love to learn, but a wiki full of tables doesn't actually give me something to work with. I think this would be useful because adding an actual slot isn't like a .REL port. This is it's own slot. (PLUS, I have SO many ideas I'd love to implement with the Ice Climber clone slot. That's SO COOL.) Having a place to start at spurs interest. And I sure as heck know I'd be doing something if I knew where to begin!