Samurai: Tank
Red Mage: Healer
Dancer: Support Melee

Now we'll have

4 Tanks (PLD/WAR/DRK/SAM)
4 Healers (WHM/SCH/AST/RDM)
2 Melees (MNK/DRG)
2 Casters (BLM/SMN)
2 Support Melee (NIN/DNC)
2 Support Range (BRD/MCH)