If you don't mind spending a bit extra, then Hydrangeas RG is flexible enough to used anywhere. 2x skill act for party when hit can allows for higher damage potential from a counter party, but can be use anywhere else as well. She can also provide dmg buff if the fight takes many turns.

With enough def buffs or debuff, she can be your dedicated tank with the help of drain from skill and guts. Max her skill, have 2 1.2x skill act and put provoke on her will allow her to 100% constantly heal.