Kowdbuff

My current favorite spot to EV train is just outside the Grand gate. Tauros for +1 atk and +1 speed, or bouffalant for +2 atk. They're lvl 52, so a little high, but you're guaranteed the pokemon you want. Once you've beat both that are just outside the gate, just go back through the gate and they're back again. Been using my spiritomb to kill them for my lower lvl pokemon, since tauros has no moves that can hit spiritomb.