Try using the dragoon to your advantage, and always keep he up in the air using jump. You really should of thought about having a white mage, but you can still work with the RM; make him be the curer at all costs, and sneak a few hits on Doga. Pound down some spells on Doga, but heal when needed. When it gets to Unei, make sure that you heal to max health, and then follow the same tactic as earlier, but less healing- only when needed.

There you go, and equip Dragoon with bloodlances to make it easier- they are found in the Ancients temple.