I already posts about FF Villians.. It is somewhere in page 3, you should check first 5 pages before post same topic but It don't matter tho.
I dont think KH2 will have FF villians as Main Villians like Scar, Jafar, Pete, etc.. I doubt that FF villians will ever to be main villians. KH1 and KH2 really shown that they will not be main villians.
It would be nice if two famous badguy from FF to be main villians like Kefka, Kuja, etc..
It would be nice if they add one of those badguy as secret boss (example: Sephiroth)
Yeah Seifer and their gang make debut in KH2 but I doubt that he would consider villians of KH, more likely rivals. Seifer is not villian in FF8, more likely puppet of Ultimica(sp?)
It would be nice if they add FF summon for FF or Square-Enix hardcore players..
Bahamut, Phoenix, Ifrit, Shiva, etc..
(mostly like they would not debut since KH is mostly focused on Disney Characters..)