My spiritomb is lvl 100 ;D and knows: Dark Pulse
Hypnosis
Dream Eater
Dark Void
It rocks.
Dark Void??? Only Darkri and Smeargle can learn Drak Void. You're pokemon must be hacked. Also, even if he could learn Dark Void, whats the point in Hypnosis and Dark Void.
As for Spiritomb, (presuming this is competitive) give him the leftovers and Bold (+def -atk) or Calm (+sp.def -atk) nature. so...
Spiritomb @leftovers
Pressure
Bold/ Calm
-Dark Pulse/ Shadow Ball
-Confuse Ray/ Nasty Plot/ Calm Mind
-Hypnosis/ Toxic/ Will-o-Wisp
-Dream Eater/ Psychic
Dark Pulse or Shadow Ball for STAB. Only use one of them since they give exact same coverage. Confuse Ray to annoy the opponant. Nasty Plot or Calm mind to increase your stats, and make battling eaisier. Toxic or Will-o-Wisp to chip away at the opponants health. Hypnosis to put them to sleep (really usefull, mine has it). Like Nachoman said, if you go for Hypnosis go for Dream Eater as well. If not go for Psychic.