Well,
there's this.
I think people mostly use him as a luxury sub for like blue or light healer teams. He should be really easy to farm with, at least. The problem he has as a leader is maintaining full HP in the face of preemptives and mobs that attack every turn. I imagine you'd need auto-healers, delays, or active skill heals (LMeta, Isis etc.) to keep up with that. There might be some hope coming his way with the new magicians, maybe?
Rei Sirius in particular. Other than that, I think people usually use him as a sub for LMeta. That team could use Raphael>Valk>Zhuge for a fully enhanced light board. I don't have light Zhuge or run healer teams so that's all I've got.