FF1
Knight, Ninja, White Wizard, Black Wizard

FF2
Frioniel, Maria, Guy, Lionheart

FF3
Ninja, Ninja, Sage, Sage

FF4
Paladin Cecil, Rosa, Rydia, Kain

FF5
Butz, Lenna, Galuf, Faris

FF6
Celes, Sabin, Cyan, Gogo

FF7
Cloud, Cid, Aeris, Vincent

FF8
Squall, Zell, Rinoa, Irvine

FF9
Amarant, Steiner, Vivi, Eiko

FF10
Auron, Tidus, Yuna, Rikku

FFT
Ramza, Orlandu, Priest, Wizard

FFT would wipe the floor with pretty much anyone. You can customize them however you want, though, so it's pretty cheap. If you take them out, it'd be between FF9 and FF10. FF9 has more firepower on their side, but FF10 has more support. I'd say FF10 would probably hold out longer.

I'm not sure what you mean by the third question either. If you mean, did I choose the characters because they were good as opposed to just being cool, then yeah, I picked them because they were strong/useful/whatever.