I very much doubt Jigglypuff will be taken out for Brawl. Not only is she an original n64 cast member, she's become almost as recognized an icon of the game as mario/link/pikachu/kirby.
Secondly, of all the pokemon characters they could add, there are few that deserve a spot more than Jigglypuff. Jigglypuff, next to Pikachu himself and Meowth of course, had probably the most regular involvement in the early storyline of the cartoons, and, if i'm not mistaken, probably still does. Many pokemon came and went during the show, but she was always around to put everyone to sleep on accident and be pissed off about it. To put it simply, there are few pokemon "bigger" than Jigglypuff. She is one of the most known pokemon, for sure.
Thirdly, there's no reason, from a smashing standpoint, to remove her. She, being only the 2nd of 2 puffball-type pokemon, and a pioneer of multiple jumps, which now appear to have been included much more freely into brawl, is indeed very unique. Certainly more unique than many other characters in the melee lineup. No one shares her moves, all of which are very unique and useful in their own ways.
I can understand you not liking a character, that's fine. But don't just assume that because you don't, that means they won't be around for brawl, especially one as big as her.
That said, Lith17, I do think they will be removing at least a few of Melee's cast for Brawl. I'm sure people are sick of just hearing "Sakurai said not everyone will necessarily return." The way I see it, in those pairs of players, those that shared the same moveset, if they were different enough to call for very different playstyles, they have a chance to remain in it. If, though, the general strategy of the two characters is the same, it's probable one is going to be gone. To me, this means Doc, Pichu, and, though it pains me to say, Y.Link. C. Falcon and Ganondorf are clearly unique enough to both stick around, and despite their shared moveset, their speeds are completely different. Marth and Roy are a tougher call, but I think they're unique enough that both might remain. However, I'm much less certain of this after a certain confirmed new arrival. And Falco and Fox? I don't know where they fall in my example. In any case, just my opinions...
