Pokémon Platinum (ポケットモンスタープラチナ ,Poketto Monsutā Purachina?, "Pocket Monsters Platinum") is a director's cut of Diamond and Pearl in the same vein as Pokémon Yellow, Crystal, and Emerald. It was released on September 13, 2008 in Japan, March 22, 2009 in North America, and was released in Australia and Europe on May 14, 2009 and May 22, 2009, respectively.

The game features Giratina as its mascot and introduces its Origin Forme, as seen in Pokémon: Giratina and the Sky Warrior. Its initial form is referred to as its Altered Forme in the English localization, but originally called its Another Forme in the Japanese release. The storyline involves a disturbance atop Mt. Coronet, as a portal to the "Distortion World" is opened and Sinnoh's climate becomes colder. The trainers have been given new outfits to suit the colder climate. The Distortion World is a strange place in another dimension where normal physical laws do not apply. In addition, Shaymin, which was distributed in Japan as part of admittance to the aforementioned film and in America through a promotion via Toys R Us, has a new form known as its "Sky Forme", a dual Grass- and Flying-type Pokémon. When traded to Diamond or Pearl from Platinum, Shaymin will transform from its Sky Forme back to its regular forme or Land Forme. With the use of a new item in Platinum known as the Gracidea Flower (unlockable with the event Shaymin) Shaymin can be caused to change from Land Forme to Skye Form, reverting with a reuse of the flower. When the special Regigigas that is given out with a pre-order ticket for Giratina to Sora no Hanataba: Shaymin is traded from Diamond or Pearl to Platinum, it activates an event that makes Regirock, Regice, and Registeel available to catch in Platinum. Like Shaymin, Regigigas was released in America via Toys R Us. Additionally, five exclusive forms of Rotom were introduced. Rotom's forms are unlockable by use of a Secret Key made available for download over Wi-Fi Connection via Platinum's onboard Mystery Gift function. Other added features include the Battle Frontier, which was first introduced in Pokémon Emerald, and appears again in Platinum with five new frontier brains; the Wi-Fi Plaza, an arcade area, the player can play minigames with other people over the Wi-Fi connection, and the Vs. Recorder which allows players to save and replay videos of battles between friends.

Pokémon Platinum sold 1 million copies in its first two days on the Japanese market. According to Media Create, the game has sold 2 million copies in Japan as of December 7, 2008. Thus, it is the fastest-selling Nintendo DS title as of late. Pokémon Platinum is the second best-selling game of Japan in 2008, as well as the best-selling Nintendo DS game in Japan of that year, selling 2,187,337 copies. On March 21, 2009, the day before the North American release of Platinum, Nintendo hosted a launch celebration at Nintendo World Store in New York. Attendees were able to demo or even purchase the game before its official release the next day. The game went on to sell 805,000 units in just 9 days in the U.S., ranking as the second highest game sales for the month. In a hands-on preview of Platinum, Kat Bailey of 1UP.com praised the game's many new features as well as its improvements in interface and graphics. "Pokémon fans probably won't be found wanting with Platinum. Even after you finish up the main quest, stop messing around with the Battle Recorder, and clear out the Battle Frontier, you've still got side quests and contests to keep you busy. And once you venture back down the Pokémon rabbit hole, you won't be coming up again for a while," wrote Bailey. Famitsu gave the game a score of 9/9/9/9 for a total of 36 points. "From the new story elements to the addition of the Battle Frontier, there's a ton of neat stuff, and you're getting a lot for your money here," they remarked.Platinum received an 8.8 out of 10 from IGN, saying it was easily the definitive version but it was difficult to praise a two-year-old game.Game Informer gave the game an 8.5 out of 10 for being "a good RPG", but also noted it's "not worth playing mostly unchanged content all over again unless you're a superfan."