Ah yes, costumes. I think that's a way they could have had a few more characters in name, by making them alternate costumes. Dr. Mario comes to mind, that could have easily been a costume for Mario. This reminds me, I'm also not against "clone" characters, at least, in concept, so long as the game has a lot of characters overall. Melee and Brawl didn't have enough to have so many clones, IMO. Also, they need to make sense. Some characters, like Mario and Luigi for example, naturally have similar abilities, but I'll never figure out how Ganondorf is anything like Captain Falcon.
I have mixed feelings about a stage editor. If it's a basic one like the one in Brawl, I'd rather not have it as it's a waste of effort. There were very few stages possible with it that had good design, and nothing created with it is as good as a professional stage. If they could make one that's more advanced, then it might be worthwhile, though personally, it isn't something I care that much about.