The game will feature Giratina as its mascot and introduce its Origin Forme, as seen in Giratina to Sora no Hanataba: Sheimi. Its initial forme is referred to as its Another Forme. The new storyline will involve a disturbance atop Mt. Coronet, as a portal to the "Ruined World" is opened and Sinnoh's climate becomes colder. The trainers have been given new outfits to suit the colder climate.
The legendary Pokémon Shaymin, which will be distributed as part of admitance to the film Giratina to Sora no Hanataba: Sheimi, will also have an alternate forme in Platinum, known as its "Sky Forme", a dual Grass and Flying-type Pokémon. When traded from Diamond or Pearl to Platinum, Shaymin will transform from its regular Land Forme into its Sky Forme with the use of a new item in Platinum. It is yet unknown what role Shaymin plays in the story of Platinum. When the special Regigigas that is given out with a pre-order ticket for Giratina to Sora no Hanataba: Sheimi is traded from Diamond or Pearl to Platinum, it activates an event that makes Regice, Regirock, and Registeel available in Platinum.