Cranidos is a gray, dinosaur-like Pokémon resembling the Pachycephalosaurus. It has a hooked beak, red irises, and a hard, blue, dome-shaped head with four spikes on its back. It has stubby arms with three claws; despite the stubbiness, it can attack with them. The back half of its body has a large, spiky pattern of blue and it has a short tail. It has feet with three forward claws and one backward.
Its main attacking prowess involves charging head-first into its opponents. When it lived in dense forests and jungles 100 million years ago, it would use headbutts to snap obstructing trees, down its prey, and combat other Pokémon like Aerodactyl. It notably lacks any intelligence.
A Cranidos is owned by Roark, which he sends out against Platinum in her Gym match. He seems to be one of the first Pokémon that he owned, having been hatched from an Egg long ago. He later evolved to Rampardos around the three Sinnoh Trainers' arrival on Canalave City. He first appeared in Putting a Crimp in Kricketot.