Dark Void, I could kinda give you the strategy...
The deck I use, has Reuniclus, and just builds up damage. I also use Telle, to trainer lock eelzone from switching. then I dama all the damage to benched, for a bench out.
The deck I battled:
Built it up on wailord, and just used switch. then did 140 damage to me, and got tons of KO's, with using the psychic Metagross, as a damage inducer.