The only new FF characters i want are Zack Fair, and Vincent Valentine... and Maybe balthier and Basch, balthier becuase hes so sexy and no one thinks he isnt ... I guess Cloud and Sephiroth are sorta tied into KH now, so nothing can take them out...
Genesis, Angeal and Zack force combined can take them out without problem.
But yeah, plot wise it'd be harder...
What about Valkyrie Profile? They kill Sora, Riku and Mickey, and the three of them would become Einherjaar.