Source 1Source 2 (Neogaf)From Neogaf:
* Pokémon Platinum, set for September release. Giratina on the box
* Volkner no longer gym leader of Sunyshore City
* The Underground is now Wi-Fi enabled
* An island called Battle Island, works in the same manner as the Battle Frontier
* Several new Pokémon 'forms' exist in the game; Giratina's Origin Form, Regigigas' Sky Form, Shaymin's Another Form
Giratina & Regigigas' new forms are said to be able to get the Levitate ability and Shaymin's Another form may be at least part Ice Type