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.
~Bulbapedia
Arceus cannot be caught in any game bar events that have already passed.
