I run my Hydreigon like this.
Hydreigon@Chopple Berry
Ability:Levitate
Modest Nature: +SpAtk, -Atk
Evs:252 Spe, 252 SpAtk, 4 def
-Draco Meteor
-Dark Pulse
-Earth Power
-Fire Blast
Chopple Berry is due to the fact that i end up dealing with pokemon who try to kill this thing with fighting more...