Kicking out Umaro + Moogle Bonanza

Umaro as an NPC wouldn't be an issue, replacing him as a character AND using him as an NPC would be.

You could replace him as a character, sprite and all, but you'd still need a basic sprite set somewhere in order for him to be an NPC, after you replaced him as a full character with a full sprite sheet of someone else.

Maybe assign that character a moogle sprite set, leaving Umaro's sprites intact and still use his character data... or the expanded sprite sheet hack to give your new character a full, formerly NPC sprite sheet. Maybe I'm over thinking that part or not explaining what I'm thinking. As a whole though, its doable just possibly not simple.