Like Pokémon Platinum, Heart Gold & Soul Silver have special details implemented within the game if you send certain Pokémon over. With this Pokémon, the Movie 12 Arceus (and other subsequent Arceus from various events around the world), you get new aspects in both Platinum and Heart Gold & Soul Silver. The special feature in this game for Arceus is much more elaborate than the Platinum one. If you trade Arceus over to Heart Gold & Soul Silver from Diamond, Pearl or Platinum and take the Arceus with you to the Ruins of Alph to later activate the special Sinjoh Ruins, you will meet up with Cynthia, the former Champion of the Sinnoh Region.