Using a drain punch belly drum set on him. Which one of the two?(covers three weaknesses so yes rock move.) and if you want the full set it's iron head belly drum drain punch and rock coverage move.
Stone edge has more power but its 80 percent accuracy can cause you to miss,though 80 is not to bad. Rock slide has more accuracy but less power, it reall depends on what you rather, more accuracy or more power.
rock slide for sure. stone edge has a higher change to miss and with chestnaught weaknesses its not a good combination. rock slide have also 30% change that the opposing Pokemon flinched