Speculation based on what I've seen for RF2 over the last couple of years:
A+ : Hazama, Beatrice, Sheryl, Hikari
A : Aran, Typhon, Greed, Orville, Viren, Mito, Garnet
B+ : Kaya, Boyd, Zen, Lud, Bazoo
Thing about the balance of RF is, it seems kinda like it suffers from GG-balance problems. In other words, most of the cast is good, but there are one or two who are so good that everyone else is weakened as a result.