So, I have battles with my step-brother and friends quite often, and I finally have my own Umbreon. I wanted it to be like an annoying Pokemon to face and to try to force them to switch out often to take entry hazard damage. This is my Umbreon as of now:
Umbreon (M) @ Leftovers
Synchronize
Bashful Nature
Faint Attack (STAB, never misses)
Toxic (Gradual Damage)
Moonlight (Healing, along with leftovers)
Confuse Ray (Lowers their chances of hurting me, and possibly hurting themselves)
I don't EV train because I don't have that kind of capability to handle it and I'll easily forget what I've trained in already.