For me personally? Make carbuncle an independent summon again. Have him auto attack and maybe give him back some of his old auto use moves. Give us all three flavors of carbuncle, even if the final results are the same.

In general? Get rid of the charge on Ifrit and give us Phoenix's heal as an independent ability. Maybe replace our revive with something Phoenix themed. Fix or remove aetherflow.

I could probably think of more but the old heads in a bit of a haze this morning.