Despite the difficulty of it I love the Barbariccia fight simply because I get a decent team. I make Cid attack and throw potions whenever Rosa gets tired.
Yang just attacks constantly.
Cecil attacks constantly and uses Cover when she uses her tornado move.
Rosa uses Cura constantly.
Kain attacks then Jumps, attacks then jumps etc.
It's a decent strategy that I used the first time I beat her and I've continued using it ever since.