Pokémon Sunday showed a preview screenshot of Pocket Monsters Platinum from next weeks episodewhich indicates that the Sinnoh Dex will expand by an additional 59 Pokémon.

Known new Sinnoh Dex numbers include: Glalie at #207, Froslass at #208, at Giratina at #210. It can also be assumed that Snorunt is #206.
Pocket Monsters Platinum will be released in Japan on September 13th and is the third Generation IV main series game.

A higher resolution image from the Pokémon Sunday episode is available on our Imageboard.