I actually thought of Heatran, but it's already been posted twice 8( Wanted to change things up a bit.
Plus I wasn't sure how to get Heatran to break through Tbolt Goodra(which I thought you posted oops)
252+ SpA Choice Specs Goodra Thunderbolt vs. 252 HP / 4 SpD Heatran: 136-161 (35.2 - 41.7%) -- 80.7% chance to 3HKO after Leftovers recovery
252 SpA Heatran Flash Cannon vs. 0 HP / 4 SpD Goodra: 93-109 (28.9 - 33.9%) -- 1.2% chance to 3HKO