This thing cannot be taken seriously in any sort of competitive play. At all. Sure, it gets a few good moves, and has decent abilities, but other than that, this thing is laughable at best. The only advantage this thing gets from it's typing is that it takes neutral damage from Steel and Water, and resists Fire, Flying, and Ice. But with a 4x weakness to Grass, and is weak to Electric, Fighting, and Ground, it can never last in RU and UU, let alone OU. This guy's only hope to be taken sort of seriously is that it either gets an evolution so it can be in Little Cup, and get usage of the Eviolite item, which increases the Defense and Special Defense of a Pokémon by 50% or 1.5%. And the only way it can be taken sort of seriously in the NU meta is to be a support Pokémon. This is my suggested spread.
Corsola @ Leftovers
EVs: 252 HP / 4 Atk / 252 SpD
- Stealth Rock
- Sucker Punch
- Rock Blast
Leftovers is pretty obvious, recover some HP each turn. Regenerator is to get some more health back when you switch out. You could also run Natural Cure, but I prefer Regenerator. You could also run psychically defensive, but the recommended set from Pokemon Showdown is for it to be specially defensive.
Stealth Rock is for extra damage on the enemy each time they switch in a Pokémon onto the field. Though beware rapid spinners such as Excadrill, and Defoggers like Skarmory.
Toxic is for even more extra damage each turn on the opponent, wittle them down more by more while you get Lefties recovery.
Sucker Punch is to get a last ditch hit on the opponent before fainting, and with 80BP, it will be sure to do at least some damage.
And Rock Blast is for a STAB move that can break sturdies and focus sashes.