I want to see a showdown between Squall and Auron. Man, that'd be awesome.
How about Tifa and Rinoa? Fist-fights ftw!
Yuna and Aeris?
Yuffie and Rikku?
Kain and Kimahri?
Jecht and Sephiroth?
Cecil and Steiner?
Oh and we have to see Cloud vs. Squall, because that'll finally put that debate to rest.

Apart from the obvious main characters, it'd be funny to see Tonberry's or Cactaurs in there. I'd love to control a Moogle, and a Chocobo lol. How about having some summons as playable characters too?
Ifrit vs. Shiva?
Anima vs. Bahamut?
The Magus Sisters vs. Knights of the Round?

Man-oh-man, I want to see this game.

I would like to see Shadow, Celes, Terra, Sabin and Cyan.

I'd like to see myself wrestling with the FF girls. I could get real nasty and stuff using my mouth everywhere. Not all the FF girls though just like Rikku and Penelo. They're the hottest ones. I'd use my mouth like everywhere, y'know? Like even in dirty parts.

As long as it doesn't prominently only feature characters from the really popular games I will be satisfied.

"As long as it doesn't prominently only feature characters from the really popular games I will be satisfied.
"

Well, if they put Kefka in the game, then how the hell is anyone gonna possibly be worth a shit?  Kefka's the best character in the FF universe!!!

Gilgamesh and Balthier would make me happy, as would what Balls said.

Moogle!