Jigglypuff is the most deserving of a cut in terms of irrelevance and an overstayed welcome, but in good conscience I'd never remove any of the original twelve characters. There's too much nostalgia attached to Jigglypuff for me, regardless of whether or not she deserves to be in the game.
I'll probably get crucified for saying this, but I think Falco is one of the least "qualified" characters on the roster. The Star Fox series itself isn't a very major one (these days, at least), and within those games Falco is sort of the number four marketed/important character after Fox, Wolf, and Krystal. He was only included in Melee because he made for an easy clone, and he stuck around for Brawl because his Melee incarnation was so popular (read: overpowered). Don't get me wrong -- I LOVE Falco, but in a game of supposed Nintendo all-stars, he's one of the least significant. Fox and Wolf would sufficiently represent the series for me.
I'll probably get crucified for saying this, but I think Falco is one of the least "qualified" characters on the roster. The Star Fox series itself isn't a very major one (these days, at least), and within those games Falco is sort of the number four marketed/important character after Fox, Wolf, and Krystal. He was only included in Melee because he made for an easy clone, and he stuck around for Brawl because his Melee incarnation was so popular (read: overpowered). Don't get me wrong -- I LOVE Falco, but in a game of supposed Nintendo all-stars, he's one of the least significant. Fox and Wolf would sufficiently represent the series for me.