That Dusclops just seems like Taunt bait to me. (At least I think it is; I can't remember if Pain Split is stopped by Taunt). Gliscor is particularly troublesome as it can even switch into Will-O-Wisp if its Toxic Orb has been activated. This is why I think you should use Night Shade over either Will-O-Wisp or Pain Split.
Night Shade allows you to wear down Pokemon that can't do anything to you faster than Will-O-Wisp will and you can use a Pokemon with Wish to get you back up to full health when you want to come back in.
(Man, Spiritomb is creepier than I thought.)
Spiritomb @ Leftovers
Trait: Pressure
EVs: 252 HP / 4 Def / 252 SDef (Feel free to try to find a better spread.)
Sassy Nature (+SDef, -Spd)
- Sucker Punch
- Pursuit
- Psychic
- Pain Split
IMO, this is the best Pokemon to trap and kill annoying Pokemon like Espeon, Alakazam, Wobbuffet, and Chandelure (mainly if you're playing Dream World). These Pokemon are often forced to do little damage to Spiritomb as it wears them down with Pursuit or outright KO's them if they switch. Sucker Punch is the priority move of choice to take out more potent threats like Specs Latios and Chandelure. Shadow Sneak would be an alternative, but Spiritomb needs the extra power as even frail Pokemon like Alakazam and Gengar aren't OHKO'd by it.
The last two moves are what sets this Spiritomb apart from the standard Choice Band set. Psychic makes this Spiritomb a good check for Fighting-types like Mienshao, Toxicroak, and Conkeldurr and means it's not set up fodder for Keldeo and Terrakion. Will-O-Wisp could go in this slot to cripple most Fighting-types as well as Steel-types that switch in, but that would do nothing to Sub Toxicroak, Keldeo, and Special Lucario and would actually benefit Conkeldurr.
Pain Split is Spiritomb's only form of recovery outside of Rest, which would be a terrible idea this gen with the new sleep mechanics. Pain Split also deals damage to the opponent and is a great move to use after Spiritomb has taken out a Pokemon. Most Pokemon can't OHKO Spiritomb if it's in good health, so it can simply take an attack from whatever comes in and take a chunk of its HP away while healing it back to enough health to take another hit when it comes back in. This makes that Pokemon much easier to take down by the rest of the team.