Ok, finished the IV boss rush. Worst was rubicante, easiest was barbarricia. I think I lost five medals total, 1,3,1,0 respectively. Retaliate retaliate retaliate. I used a lunatic high rw this time, used on rubicante and barbarricia. Rubicante I had to save load a ton until I got one where he only used his aoe once or twice. I used lunatic high and then blizzaga and water strike in quick succession before the cape closed. Was lucky with timing and only healed him once. Milon was easy, I used two curajas on offense and then retaliate. Caignazzo took forever, was on his shell way too much and I ran out of blizzagas, but he wasn't to much of a threat. Barbarricia became a tornado twice, so wasn't too bad, that one was over far faster than the others even though you can't hit her with spells.
If you can master this dungeon without using retaliate, you are a far superior tactician than I. Counters counters counters.