Rhyperior @ Zoom Lens
Ability: Solid Rock
EVs: 252 Atk / 252 Def / 4 HP
Brave Nature
- Drill Run
- Stone Edge
- Hammer Arm
- Megahorn
Make sure Rhyperior has as low a speed as possible (it has a terrible speed stat so don't expect to outspeed something normally) therefore giving all of its' moves a 20% increase in accuracy if you move last - which you should - meaning you give Rhyperior for powerful attacks with worse accuracy.
- Drill Run = 80 BP, 100% accuracy, STAB, a high-crit ratio (better than 20 extra power [preference]).
- Stone Edge = 100 BP, 96% accuracy, STAB.
- Hammer Arm =100 BP, 100% accuracy, lowers your speed (good in this instance).
- Mega Horn = 120 BP, 100% accuracy.
Put this guy on a Sun Team - as your physical tank - to reduce his/her weaknesses to a great extentdue to the combination of Solid Rock, Sun reducing the power of water and fire types being able to cover your weakness to grass attacks with 2x the power on their STAB fire moves.
Rhyperior @ Life Orb
Ability: Solid Rock
EVs: 252 HP / 252 Atk / 4 Def
Adamant Nature
- Earthquake
- Stone Edge/Rock Slide
- Avalanche
- Thunder Punch
This is really just a standard moveset for Rhyperior with 2 powerful STAB moves, Thunder Punch to cover his/her water weakness and Avalance to cover his/her fire weakness. Avalance is close in power to Megahorn but only when you attack after the opponent which is why some people prefer Megahorn. Make sure to put this guy on a Sun Team as your physical tank for reasons already explained.
It is personal preference but I say MEGAHORN with the above moveset
EDIT:
Don't use Rock Wrecker
Rock Wrecker is best used: as a last resort to finish a battle, just before you die or combined with a Choice Band if you switch out afterwards otherwise you can hit twice with Stone Edge and deal more damage rather than hit once with Rock Wrecker and Recharge/Switch.