Dialga

Dialga is the Legendary Pokémon at the center of Pokémon Diamond, as Palkia is of Pearl. In the story, Team Galactic uses crystals taken from the three Mirage Pokémon of the lakes to make the Red Chain, which can control Dialga, and its leader summons it at Mt. Coronet; the player then battles it, and Sinnoh returns to normal after it is defeated or caught. In Pokémon Platinum both Dialga and Palkia can be caught after the game is completed.