Although it has massive base attack, I really reccomend you ditch Rampardos, with such low speed, low defense and many weaknesses it' can usually be 2OKO'd even if it does get a rock polish up, it's the definition of a glass cannon. But still I won't be useless so here's my favourite set for him, he's hard not to ignore with the second highest base attack (165, only second to attack form Deoxys) in the game;
Rampardos @ Choice Band
~ Head Smash
~ Fire Punch
4 Hp | 252 Atk | 252 Spe
Head Smash broken down is this; 165 base attack + 150 base attack power + STAB + Choice Band = Death. Although the recoil won't be nice. Fire Punch is for Ferrothorn and Skarmory etc whilst Pursuit can hit anything trying to escape, hope I helped.
EDIT: Hydreigon also works better with either Modest or Timid nature, and use Choice Scarf or Specs as an item, or even Life Orb.