I've used the following set with a great deal of success on the ladder:
Scolipede @ Salac Berry
4 HP/ 252 Atk/ 252 Spd
Swarm +2 Megahorn is nothing to laugh it, and Aqua Tail hits a lots of bulky grounds as well as terrakion hard, also being boosted by rain.
Veni, Vidi, Vici.
Credit to for Plus for the awesome avatar.