I like Bacon on 07 November 2009
All you need is a Pokedex in the game. and you get that in the first 15 minutes of the game!
When you are near the DS that is giving out the event, while you are on the file selection screen it will tell you that there is a Myster Gift near by. This is assuming that you don't already have Mystery Gift unlocked. Just being near the event will unlock Mystery Gift. You can unlock it manually, but you don't have too. Mystery Gift is one of the options on the File select screen.
You just go to receive via wireless and bam you got your wonder card for Arceus. Go to a Pkemart and get your level 100 Arceus.
www.pokemon.com has more info.
