hm... it's a good strategy, but what if Cresselia gets K.O.'d before you get a chance to trade abilities?
But I do agree with sumwun, it depends on the rest of your team.
For doubles, this is my team:
Toxapex(Ability: Merciless/ Moveset: Recover, Baneful Baunker, Poison Jab, Scald/ Item: Poison Barb)
Salazzle(Ability: Corrosion/ Moveset: Flamethrower, Attract, Toxic, Sludge Bomb/ Item: Charcoal)
Passimian(Ability: Receiver/ Moveset: Low Sweep, Brick Break,Brutal Swing, Substitute/ Item: Black Belt)
Oranguru(Ability: Telepathy/ Moveset: Shadow Ball, Trick Room, Psychic, Substitute/ Item: Lax Incense)
Primarina(Ability: Torrent/ Moveset: Hydro Pump, Sparkling Aria, Sing, Dazzling Gleam/ Item: Primarinum Z)
Toucannon(Ability: Skill Link/ Moveset: Drill Peck, Bullet Seed, Fly, Protect/ Item: Sharp Beak)
Toxapex+Salazzle (Salazzle poisons other Pokemon, then Toxapex gets a lot of crits due to Merciless)
Passimian+Oranguru (Oranguru uses Trick Room to increase Passimian's SPEED, Passimian can use Brutal Swing and wont harm Oranguru)
Primarina+Toucannon (Primarina uses Sing and lets Toucannon get a few hits in. Z-Move for extra power)
(Toxapex+Oranguru+Trick Room) (with the others, there really isn't a strategy, just get in a few more swings)
So yeah, it really depends on the rest of your team.