only with action replay!!!
there is no way without action replay
Trade from Diamond, Pearl, or Platinum
You can't
hall of origin
Good question the answer is Mew, Mewtwo Arces
If you mean Arceus, you will have to blow the Azure Flute, which you get only by Mysterious Gift or you can use cheats (Action Replay), on the Spear Pillar, found at the top of Mt. Coronet.
well you can get Shamin Arces Darkrai Creslia and Regigagis
TO GET ARCES HOPE THAT HELPED A LOT
get the azure flute and then go to where you met dialga and play it
ponyta and rapidash.
arces,palkia,dialga,garitina,ect.
pokemon diamond. get the azure flute play it at the top of mout cornet. or spear pillar. it is at lv 80
I think it's Arces IDK if it is but I'm thinking it is but good luck trying to find the answer your looking for alright!!!! POKEMON!