Rotom Secret Key Event!

I have caught wind of a new Pokemon event concerning the Secret Key, which allows you to obtain a Rotom that can change into one of five different forms. It will be taking place at Toys 'R' Us from April 20th to May 12th, but can also be downloaded in Platinum.

I'm not actually sure if the key allows you to obtain the Rotom in the first place or simply changes it. I'm trying to avoid as many spoilers for Platinum as I can right now, as I have yet to play it. (I have to play through Fire Emblem first. XP) I am not sure the download will work for Diamond and Pearl, so those who have no Platinum will have to head over to Toys 'R' Us to get it.