VII:
Cloud = Fighter
Cid = Dragoon
Aerith = White Mage
Tifa = Monk
Yuffie = Thief/Ninja
Red XIII = Red Mage?
Vincent = Gunner/Berserker
Barret = Gunner
Cait Sith = Gambler/Beastmaster

VIII:
Squall = Fighter
Zell = Monk
Quistis = Blue Mage
Rinoa = Black Mage (Angel Wing)
Irvine = Gunner
Selphie = Gambler

X:
Tidus = Fighter/Time Mage
Auron = Samurai, though his Breaks are from the Warrior class
Lulu = Black Mage
Yuna = White Mage/Summoner
Rikku = Thief/Alchemist
Kimarhi = Dragoon/Blue Mage
Wakka = Archer/Green Mage