Dialga

Dialga is a Steel-Dragon Type Legendary Pokémon introduced in Generation IV. It is also the Version Mascot of Pokémon Diamond. Dialga is a member of the creation trio, along with Palkia and Giratina.

Pokémon Diamond, Pearl and Platinum
Dialga was going to be used by Cyrus to destroy the world, until Uxie, Mesprit and Azelf destroy the Red Chain which would have created the new universe. Afterwards, a battle with Dialga will initiate when playing Pokémon ''Diamond. It cannot be battled in Pokémon Pearl. In Pokémon Platinum, ''Dialga can be battled in the post-game along with Palkia. Its signature move is Roar of Time.

Super Smash Bros. Brawl
Dialga appears in the stage Spear Pillar as a stage hazard, where it can shoot beams, slow down time or distort the stage. Aside from that, it is a trophy.

Trivia

 * Dialga is the 483rd Pokémon in the National Dex.
 * It was said that time started to move when Dialga was born.