I had a Gengar, a Scrafty and a Granbull. The latter two could withstand a few of its Dark Pulses whilst drawing out its other attacks that didn't effect Gengar, so I kept swapping between them.
Started with Gengar to lure out Dark Pulse. Switched to Scrafty, Dark Pulse is not very effective and it would then line up Focus Blast, which I dodged by switching back to Gengar. I continued this till his only move left was Recover, at which point I brought out my Samurott with Fury Cutter which quickly out damaged his recover.
Easy battle with this strategy.
