I'd change the EV spread from 4 Def to 4 Sp.Def, since Rhydon isn't exactly hurting in the Defense department, and it's most vulnerable to special attacks. Also the Speed IV should be set to 0, since Rhydon is meant to operate in Trick Room.
I'm not sold on Drill Run over Earthquake. It's only 5 BP more than Earthquake against a single target (factoring in doubles damage penalty), and 5% less accurate. It is also more susceptible to Protect than Earthquake (since an opponent would have to double Protect to guarantee no damage). True, your partner needs a means to avoid Earthquake as well, but good teambuilding makes this a non-issue.
Black FC: 2537-3042-2350
VGC2012 Analysis: Slowbro