While it is similar to other legendary Pokémon in Pokémon Diamond and Pearl, including its post-National Dex appearance and lack of relation to the games' overall plot, it was revealed in early February, 2008 to have an alternate form known as the Origin Forme, in addition to the form it takes in Diamond and Pearl, the Altered Forme. It is in this new form that Giratina took its place as version mascot of Pokémon Platinum, the third version of Generation IV.
It is not known to evolve to or from any other Pokémon.
As first revealed by Japan's CoroCoro Magazine, Giratina has two forms. The first (Altered Forme) is the form that appeared in Pokémon Diamond and Pearl. In this form, Giratina is has a large, gray, centipede-like body with six short legs. Its legs have gold claws and gold bands on them. It has a tail and a thick black stripe running vertically along the front of its body. There is a series of red horizontal stripes running across the large black one. Three gold half-rings circle the back half of Giratina's neck at the same points that three of the red stripes are at on its front, resembling a ribcage. On its back are two large, black wings that are decorated with red, conical objects that also could be claws. The wings seem oddly out of place, due to the fact that Giratina seems far too heavy to fly effectively. The wings also seem to be ghostly, as they can change shape as if they were made of a liquid.
Giratina's head and eyes resemble those of Dialga and Palkia, causing many to theorize that it is related to the two. This assumption is confirmed in Pokémon Platinum. Giratina's Template:Shiny2 form is nearly opposite in color compared to the original. The colors of the shiny Origin Forme is the same as the Altered Forme's except for the wings which appear to be a dark shade of brown.
The second is a new Origin Forme which made its debut in Giratina and the Sky Warrior; it uses this form when traveling through dimensions other than ours, such as the Distortion World. The form-altering is triggered by a change of gravity. This form is more serpentine than Giratina's Altered Forme. The Origin Forme of Giratina has six black streamers on its back that each have a red spike at the end. Its mouth is hidden by the head plates, which swing open sideways when the mouth is opening. Giratina's legs have been reduced to spike-like protrusions. There are four more golden spikes near the edge of the tail. This version of Giratina also appears in Pokémon Platinum, and can be activated outside of the Distortion World if it is holding a Griseous Orb.
Giratina's body is likely made up of antimatter, like all things from the Distortion World.
In Platinum, Giratina can transform to its Origin Forme by equipping the Griseous Orb. If the orb is unequipped in battle, it goes back to Altered Forme. The Origin Forme has higher offensive stats while the Altered Forme has higher defenses. Since Giratina's Origin Forme (and the Griseous Orb, for that matter) is exclusive to Platinum, when it is traded to Diamond or Pearl it will revert back to its Altered Forme, and the Griseous Orb it was holding goes back into the player's bag.
Giratina is able to control dimensions besides those of time and space.
When in its Origin Forme, it is able to pass through dimensions at will, however, it will turn back to its Altered Forme due to the gravity change from the Reverse World. It does so by emitting a whirlwind from its mouth which creates a portal.
It also seems to have a connection to reflective objects, such as mirrors and pools of water. Reflections embody the concept of an antimatter world.
Judging by the events in Pokémon Platinum and Giratina and the Sky Warrior, its portrayal in ancient folklore, and its Platinum Pokédex entry, it's assumed that Giratina is a highly aggressive Pokémon protective of its home. It should be noted that despite the legends depicting it in a more evil light than the others in its trio, Giratina arrived at Spear Pillar to save the world from Cyrus' attempted apotheosis; though it may have arrived to protect its own world from destruction.
Legends claim that Giratina appear in cemeteries and that this Pokémon species supposedly lives in the spirit world, on the reverse side of ours. It was banished for violence.
Giratina made its anime debut in Giratina and the Sky Warrior. In the movie, Giratina ambushes and drags Dialga into the Reverse World in order to exact revenge against the Temporal Pokémon for causing damage to it during its fight with Palkiasome time before. Zero also attempts to copy Giratina's powers in order to take control over the Reverse World. Throughout the movie, Giratina takes on its Origin Forme whenever it is in the Reverse World, and its Altered Forme whenever it is in the real world.
| colspan="13" | Bold indicates a move that gets STAB Italic indicates a move that gets STAB only from an evolution of this Pokémon A colored initial indicates that the move is not available to be tutored in this game, while a colored background indicates that the move is available.
Giratina is one of very few non-Template:Type2 Pokémon that is able to learn Fly. The others are: Vibrava, Flygon, Latios, and Latias (all four of which have the abilityLevitate), Mew, Smeargle, and Arceus (all three of which can learn all HM moves). It is the only one who does not permanently keep Levitate. Additionally, before the revelation of its Origin Forme, it was unique in learning Fly but not having legitimate access to Levitate at all.
Giratina is the only one of its trio without a jewel located somewhere on its body.
Giratina is considered to be the forgotten one among itself, Dialga and Palkia, even though all three were created by Arceus.
Giratina is the only Pokémon that is able to hold the Griseous Orb; a Ditto that transforms into an Origin Forme Giratina during battle will immediately change back into Altered Forme (unless in battle with it in the Distortion World).
If it is defeated a second time in the Turnback Cave battle, it will reappear in one week for another battle. It shares this trait with Heatran. However, the items rewarded for completing Turnback Cave's maze will be unavailable during this time.
Giratina is the only Pokémon at the end of a regional Pokédex listing that is not an event-exclusive Pokémon.
Giratina is possibly based on a basilisk. In the Altered Forme, the wings may be based on a bat's, and its body has an insect-like, six-legged feature, but its posture is similar to a sauropod. Its Origin Forme has a body similar to a serpent, while the six protrusions on its body may be based off of a scorpion's stinger.