Detailed Result:
252 +6 SpAtk Choice Specs Heatran Overheat vs 0 HP/0 -6 SpDef Paras: 72502963.64% - 85297636.36%
100% chance to OHKO
Possible HP Damage: 7975326, 8069154, 8162982, 8256810, 8350638, 8444466, 8538288, 8632116, 8725944, 8819772, 8913600, 9007428, 9101256, 9195084, 9288912, 9382740
...Even I didn't expect it to be this high lol. This is the most powerful any move can get in the game.