That was one of the bosses that ticked me off the most...it's been a while so i can't tell you what levels my characters were...but seeing as I only used Vaan, Ashe, and Bashe throughout the game (yes foolish but i managed to get through it ><)

All i did was stock up on phoenix downs and remedys and make sure you have remedy lore 2/3 whichever heals doom status and maybe set gambits to auto-use them if you think its necessary