Planned set: 252 Sp.atk/252 Spd/4 Hp Ability: Intimidate ---> Aerilate -Hyper Voice -Hydro Pump -Fire Blast -Dragon Pulse
Well since you have a special set then the nature should be either Modest or Timid. Modest is for when you need that extra power, and Timid is for when you need to get some speed. And change the 4Hp EVs to 4Spe because you will be taking less damage from Stealth Rocks. Hope I helped!