Surprisingly i didn't start out with the idea of the rain, so my first choice was Heatran, this was his set:
Heatran @ Focus Sash
Trait: Flame body
Evs: 252 SpA, 252 Spe, 4 HP
Nature: Timid (+Spe -Atk)
-Stealth Rock
-Roar
-Magma Storm
-Earth Power
I wanted a lead that could set up...