Rameidon

Diamond: Its powerful head butt has enough power to shatter even the most durable things upon impact.

Pearl +2: Its skull is as hard as iron. It is a brute that tears down jungle trees while catching prey.

Platinum +4: If two were to smash their heads together, their foot-thick skulls would keep them from fainting.

HeartGold +3: Its skull withstands impacts of any magnitude. As a result, its brain never gets the chance to grow.

Sun: The result of repeated headbutts is a skull grown thick and hard. However, its brain has shrunk in size compared with Cranidos’s.

Moon: Records exist of a revived fossil that evolved into Rampardos. It proceeded to escape and then destroy a skyscraper with a headbutt.

Ultra Sun: In ancient times, people would dig up fossils of this Pokémon and use its skull, which is harder than steel, to make helmets.

Ultra Moon: This ancient Pokémon used headbutts skillfully. Its brain was really small, so some theories suggest that its stupidity led to its extinction.

Legends: Arceus: Very little is known about its biology. Can knock down massive trees by smashing its beautiful, pearl-like crown against them.