As simplistic as the game should be:
Gladiator >>> Paladin
Gladiator >>> Templar
Gladiator >>> Viking
Gladiator >>> Ninja
Gladiator >>> Beast-master
Gladiator >>> Fencer/ Musketeer
Marauder >>> Dark Knight
Marauder >>> Samarai
Marauder >>> Berserker
Marauder >>> Viking (version 2)
Marauder >>> Templar (version 2)
Ninja >>> Thief
Ninja >>> Dancer
Ninja/Beast-master >>> Blue Mage
Pugilist >>> Monk
Pugilist >>> Puppet-master
Con/Thm >>> bard v.1,2,3,4 or 5
Fenc/Con/Temp >>> Red Mage