While it is not known to evolve into or from any other Pokémon, it will change type when it is holding a Plate.
Like Darkrai and Shaymin before it, Arceus was not officially recognized by Nintendo until February 14, 2009, the year of its debut movie. It was officially revealed to international audiences on August 3, 2009.
Arceus is known as "The Original One", as it is said that it created Sinnoh and Ransei, and possibly the entire Pokémon universe, along with the lake guardians and creation trio.
It is the trio master of both the lake guardians and the creation trio.
This section temporarily contains information copied directly from Bulbapedia, and needs to be rewritten so not to be classified as plagiarism.
Arceus is a white equine resembling a qilin or centaur with a gray, vertically-striated underside. The striated pattern has similar recurrences on the underside of its mane, tail, and face. Its four pointed feet are tipped with gold hooves. Its long mane juts away from its head, and its face is gray, with green eyes and red pupils, and a green circular pattern below its eyes. Arceus also has a streak of gold coloration on its head, and ears that point upward. Its neck is fairly long, with two pairs of extrusions to the sides, and a flap-like feature on the neck's underside that is colored white like much of the body. It also has a golden cross-like wheel attached to its body by its round abdomen, which changes color along with its eyes and hooves based on Arceus's current type, which depends on the plate that it wields. The wheel also has four jewels attached to it. The pattern of striated gray of Arceus's underbelly resumes past Arceus's waist. Its limbs have gray undersides and extrusions at the tops of the legs. Arceus's tail is fairly like its mane in shape and coloration. According to legend, it shaped the Pokémon universe using its 1000 arms.
Arceus is thought to have created the Sinnoh region and possibly the entire Pokémon world, the lake guardians: Uxie, Azelf, Mesprit, and the creation trio: Dialga, Palkia, and Giratina. Because of this, Arceus is thought to be one of the most long-lived of all Pokémon species. It has the power to recreate the creation trio as well, presumably to guard the dimensions when a Trainer has caught one of them. According to the anime, its power can also bring back things that it once destroyed, make certain things vanish into thin air, or to halt time.
Arceus is shown to care for and safeguard the planet in ancient times and protected it from cataclysms such as meteors, and it would show gratitude and compassion in return to those who treated it with equal kindness. Arceus does not suffer fools gladly, and it will attack in a violent rampage if betrayed or deceived. It also holds long grudges if betrayed by those it considered friends. In Arceus and the Jewel of Life, it is said to "feed" off the energy of the elemental plates. It is the only known Pokémon that can learn Judgment.