Cobalion (Japanese: コバルオンKobaruon) is one of the generation V legendary foursome along with Terrakion, Keldeo and Virizion. It is a Steel/Fighting type. They used to be three, Cobalion, Terrakion, and Virizion, until they rescued Keldeo from a forest fire. It is known as the Iron Will pokemon and bears a close resemblance to a markhor.
The first part of this Pokémon's name is a reference to a metal, Cobalt. This is also a reference to the fact this Pokémon is a Steel Type Pokémon, as well as the Pokémon's color; Cobalt, a shade of blue.
Cobalion along with Keldeo, Terrakion and Virizion seem to resemble Entei, Suicune, and Raikou by them all being able to walk on four legs, they are all legendary that can be used in the Gear Station, and they all seem to be tied together. Additionally, Cobalion is the same height as Entei, Terrakion is the same height as Raikou, and Virizion is the same height as Suicune.
Cobalion is the first Fighting-type legendary besides Arceus's Multitype in the Pokedex.
The Best Pokéball to catch this Pokemon in (as well as Terrakion) is the Dusk Ball.
Though this is no longer the case in Pokemon Black 2 and White 2 as both are now found on Route 13 and Route 22 respectively.
Cobalion is one of the main antagonists in Pokemon Rumble Blast. But later, turns out to be a hero as he was trying to save all the toys from Dark Rust.