It looks like none of the Contrary users have anything relevant to use, unless you want to try sweeping with Dragon/Fire-spamming special Spinda. The problem with a V-create + Stored Power set is that most other Gen 5 Pokemon outclass it, as Quiver Dance and Shell Smash are widely available -- Swoobat gets STAB, Simple, and Special Attack. If you want a bulky Speed-boosting set, you could run Quiver Dance/Stored Power Leftovers Musharna invested in physical Defense, which serves mostly the same purpose. A bulky phasing set might work on Serperior if Gen 5 had any relevant recovery moves, as unboosted Horn Leech coming off base 75 Attack won't be able to mitigate enough damage even with Leftovers. This is the best I can think of running.
Serperior @ Leftovers
Ability: Contrary
EVs: 252 HP / 4 Def / 252 SpD
Sassy Nature
- V-create
- Dragon Tail/Circle Throw
- Horn Leech/Circle Throw/Dragon Tail
- Scald/Stored Power
Phasing moves have negative priority, so the speed boosts from V-create are kind of pointless, but they're nice to have anyway. You'll get walled by a type no matter which phasing move you choose, so pick your poision. Horn Leech gives you (weak) recovery and (weak) STAB, so you can either run it or the second phasing move to dissuade Fairy and Ghost types. Scald spreads burns, which is always nice, and Stored Power does...mediocre damage even at max power. You can't reliably 2HKO yourself.
0 SpA Serperior Stored Power (380 BP) vs. 252 HP / 252+ SpD Serperior: 160-189 (45.1 - 53.3%) -- 35.5% chance to 2HKO