If anyone has Pokemon Platinum and cares to get the other forms of Rotom here is a link that will apparently tell you how.
http://www.pokemonplatinum.com/#/pokemon/rotom/I tried it and it works but go fast if you want it you only have until July 19th or your out of luck.
When the site loads there should be a link near the bottom right of the screen that says "Learn more about the secrete key" Click that link and it will give you directions on how to get this.