Guzzlord

Guzzlord is a Dark, Ghost-type Ultra Beast from the Alola region. It does not evolve into or from any other Pokémon. Its codename is UB-05 Glutton.

Trivia

 * Despite being a Dark/Dragon-type Pokémon in the main series, Guzzlord is listed as Dark/Ghost in the Pokémon GO game files. This is most likely a mistake.