I´ve been using this moveset for a while, and results have not been bad:
Nature: Careful
Hability: Prankster
Item: Leftovers
EVs: 252 Def, 252 SpD, 4 Spe
Moves: Light Screen, Cotton Guard, Leech Seed, U-Turn
Basically, first turn I use Leech Seed. If I have half or less of my total HP , next...