Spiritomb: Impish or Careful? I'm running this set:
-Hypnosis
-WoW
-Sucker Punch
-Shadow Sneak
Spiritomb is very good at countering psychics and ghosts. I would go with careful for this purpose, especially since you have Will-O-Wisp for punishing physical sweepers who come in and try to set up on you. Remember not to burn Heracross, guts Machamp, or guts Hariyama though. Using Hypnosis as your initial status move would be a good idea if you suspect one of these is waiting to switch in on Spiritomb.