Rampardos might be the best rock type attacker

With base stats of 295 ATK 114 DEF 194 HP, and the possibility of charge moves such as Rock Slide , Stone Edge and hopefully, the infamous Head Smash with a Base power of 150, the only downside it having no access to STAB fast moves (other than hidden power rock). Hopefully Niantic will not include Ancient Power or Rock Tomb which might severely limit this Pokemon's potential