I've been working on a set made for sweeping that plays off of Contrary:
EVs: 252 SpA/252 Spe/4 HP
Nature: Timid
Item: Life Orb/Leftovers
* Leaf Storm
* HP Fire/HP Ice
* Giga Drain/Leech Seed
* Substitute
Leaf Storm is the obvious STAB choice for a Contrary set due to the +2 SpA with each use. HP Fire is there to hit any Steel types that can withstand the STAB moves, or you can use HP Ice to deal with Flying and Dragon types. Substitute buffs his already decent survivability, with either Leech Seed or Giga Drain for recovery; Giga Drain is a little better with the SpA boosts, but Leech Seed can both force switches and help whittle down Pokemon that resist Serperior's other moves.
Life Orb makes Serperior's Leaf Storm-boosted attacks even more monstrous, and the recoil can be easily healed off with Leech Seed or Giga Drain. If you'd rather have extra recovery, Leftovers work just as well.
Of course, actually getting this Serperior is a bit of a challenge for me since the Snivy I started with had absolute crap for IVs, and all of his kids followed suit. Hopefully the shiny DW Serperior I picked up at Anime Punch will help alleviate this...
EVs: 252 SpA/252 Spe/4 HP
Nature: Timid
Item: Life Orb/Leftovers
* Leaf Storm
* HP Fire/HP Ice
* Giga Drain/Leech Seed
* Substitute
Leaf Storm is the obvious STAB choice for a Contrary set due to the +2 SpA with each use. HP Fire is there to hit any Steel types that can withstand the STAB moves, or you can use HP Ice to deal with Flying and Dragon types. Substitute buffs his already decent survivability, with either Leech Seed or Giga Drain for recovery; Giga Drain is a little better with the SpA boosts, but Leech Seed can both force switches and help whittle down Pokemon that resist Serperior's other moves.
Life Orb makes Serperior's Leaf Storm-boosted attacks even more monstrous, and the recoil can be easily healed off with Leech Seed or Giga Drain. If you'd rather have extra recovery, Leftovers work just as well.
Of course, actually getting this Serperior is a bit of a challenge for me since the Snivy I started with had absolute crap for IVs, and all of his kids followed suit. Hopefully the shiny DW Serperior I picked up at Anime Punch will help alleviate this...