Yeah, I can forsee the palette swaps having more minor changes to them, a la Peach-Daisy. I don't think it's the hardest thing in the world to do alternate costumes, but it is programming work, and the kind that the team would probably only do if they had extra time before the release; Brawl, alas, seems to be coming down to the wire. Plus, with as many characters in the game as there'll probably be, there'd be, like 50 costumes. And they'd all have to be differentiated noticeably by color, lest we forget. Twilight and Ocarina Links won't look too different from far away, I'd wager.