At a 3vs3 tournament I took part, I use Sashed Butterfree, specs Omastar and Shedinja. Got second place with that.
Butterfree uses Sleep Powder, then Rain Dance. If she isn't killed next turn, U-Turn to Omastar and destroy everything with Surf. Shedinja is good on 3vs3 because you can't have full coverage- I killed more than one Blissey with it, and it's a perfect switch-in on Choice users.