This is all the information that is currently known about Pokemon Platinum. This information may change before the game is actually released. Most, if not all, of what is displayed here has been gathered from the official Platinum site, videos, magazine scans, and the like

• The name of the third game to the DP saga is called Pokemon Platinum and will be released on September 13th, 2008 in Japan.
• Giratina is now part of the main storyline, although its role is unknown
  • It has two forms, the Origin Forme and the Another Forme. It
    • The Origin Forme is lighter and taller than the Another Forme
    • The Origin Forme can learn new moves such as Mudslap and Outrage
    • The Origin Forme has the Levitate ability
    • The Origin Forme is only available when in the Torn World
  • It can be obtained at level 47 rather than 70.
  • It will most likely be capturable before the Elite Four challenge, similar to Rayquaza in Emerald
  • It resides in the Torn World, a new location, rather than Turnback Cave
  • It is not known yet if Giratina can toggle between its forms like Shayman can
• Dialga and Palkia make in-game appearances
  • It is not known if Dialga and Palkia will be capturable in the game; if they are, it may be in a manner similar to Groudon and Kyogre in Emerald.
  • If they do appear, their levels and moveset are unknown
• Shaymin has two forms, the Land Forme and the Sky Forme
  • The Sky Forme has the Serene Grace ability
  • The Sky Forme learns several new attacks like Air Slash and leaf Storm
  • The Glacidia Flower item allows Shaymin to toggle between its forms
    • This item only works during the day and if Shaymin isn't frozen
• Two new characters are introduced
  • Handsome is an undercover spy trying to learn the details of Team Galatic
  • The unnamed man is a professor who works for Team Galatic
• Sinnoh has a radical dip in temperature, causing snowfall all over the region
  • As a result, Lucas, Dawn, and the rival all receive clothing fitting for cold weather
• The Poketch gets a graphical update
• The Torn World is one of many new areas introduced; it is home to Giratina
• Regirock, Regice, and Registeel are obtainable in-game
  • Apparently this requires a special event Regigigas to be able to capture them
  • These Pokemon will be at level 30
  • It is unknown if the Regigigas is actually required.
  Pokemon sprites have been redone
  • Sprites are still animated, and still two frames with distortion
  • Pokemon back sprites are better animated
  • The sprites for gym leaders and other important people have a battle animation
• The Global Trade Station has been revamped
  • Wifi has the Wifi Square where players can play games
  • The GTS now has an e-mail feature
• The Battle Frontier makes a return
• Team Galatic appears more times
  • The headquarts has been revamped
  • The groups plans have been changed
  • Cyrus is more open about the goals of his organization
• Cities and other locations receive graphical updates
• Pokemon Gym are completely revamped
• The HP, level, and gender status bars are revamped
• The player teams up with the rival to battle Volkner and Flint
• When the player engages battle with important trainers, a small banner appears across the screen displaying "Vs." and a detailed image of the character