Right now I'm using a specs set, with Draco Meteor, Flamethrower, Dark Pulse, Flash Cannon. It hits pretty hard, but is better to save him for mid/late game. And I realized that often Dark Pulse is the safest choice, usually is the one move with less resistance in opposing teams.
I've used a Specs Hydreigon and it hits really hard. But I'd switch Flash Cannon for U-Turn, or one of Surf or Earth Power. But I prefer a Life Orb 3 attacks + Roost over Specs.