ARCEUS … how do you even say that by the way… Ar-Ce-Us? Thats actually easy I guess… so anyways

ArCeUs will finally be available to catch in Pokemon Diamond, Pearl, and Platinum! All 3! So make sure you hit up a Toys R Us sometime between November 7th and November 15th. that’s 1 week.
If you have Platinum it will unlock a special event, just like it’s been for the last few events. I’m guessing Diamond and Pearl will have the boring “Pick it up at the pokemart” thing… well that’s the lazy way too.

So be sure to check that out!

serebii.net also reports trading Arceus into future Heart Gold and Sould Silver games will unlock special locations were you can obtain a Level 1 Dialga, Palkia or Garatina. Crazy ish.