First off, get rid of Horn Drill. It is less usefull than many other attacking moves. And if it misses, your screwed. Keep Earthquake. Change out Sludge Bomb for Poison Jab due to Poison Jab being physical. Then teach it Shadow Claw to counter Psychic types. And as a last slot, go for Brick Break to hit pesky Ice types. I know I am changing your set a lot, but to be honest, yours did suck.
