This Pokemon has been very exclusive and almost impossible to get. But now, till May 1st, you can get it for your Black/White Version. See more information on the actual Global Link Website http://en.pokemon-gl.com/
You need to go to Entree Forest(after you have tucked in a Pokemon) and you should find Arceus in the forest. You can capture it with any pokeball so you don't need to worry that it's a level 100 Pokemon. For some reason my forest was empty today but my husband was able to get Arceus so this does work, it's a global event!
