By going to the Mystery Gift option on the main menu of Pokemon Heart Gold and Soul Silver for the Nintendo DS, Trainers will receive an item that will gives an opportunity to capture the legendary Latios or Latias.
Depending on the version, the player will receive the Enigma Stone via the Nintendo Wifi Connection. In order to use the Enigma Stone, the player must have beaten the Elite Four, obtained a National PokeDex, and have at least a one or two Wondercards.
Obtaining the Enigma Stone is only for a limited time. Get yours today before the promotion ends this August 27th.