Sandstorm abuse and Stealth Rock setters.
Rock is the type that defined the single most impactful competitive move ever printed: Stealth Rock. Entry hazards have shaped every generation of VGC and Smogon metagame since Gen 4, and Rock is the setter type. Beyond hazards, Rock pairs with Ground for sandstorm teams — Tyranitar's Sand Stream ability and the 50% Sp. Def boost Rock-types get in sand define an entire archetype.
Rock is a hazard-setter, physical attacker and weather abuser type. Tyranitar, Hippowdon and Stonjourner form the sand backbone. Weakness Policy Tyrantrum, Choice Band Rhyperior and Assault Vest Coalossal are the three most common offensive archetypes.
Stone Edge (100 BP, 12.5% crit) is the physical nuke. Power Gem is the special option. Accelerock gives Rocks priority. Stealth Rock is the hazard move every team needs a setter for.
Rhydon was the first Pokémon ever created in the franchise's history — Ken Sugimori's original prototype sketch, designed before Bulbasaur or Pikachu existed. Its Pokédex number #112 has nothing to do with its creation order.