Mesprit

Mesprit is a region-exclusive Psychic-type Legendary Pokémon from Sinnoh region. It doesn't evolve into or from any other Pokémon. Along with Uxie and Azelf, it is a member of Lake Guardians.

Trivia

 * On April, 2019, there were reports of the Mesprit and the other Lake Guardians appearing in the wild.