Gimmighoul is a Pokémon that comes in two forms: Chest and Roaming. Chest Form Gimmighoul is a Ghost-type Pokémon that weighs 11 lbs. (5.0 kg), is 1' (0.3 meters) in height, and has the ability Rattled. A similar breakdown has not yet been given for Gimmighoul's Roaming Form as of writing, but is is expected to share its Chest Form's Ghost typing.
Gimmighoul's Chest Form has the power to possess people to do its bidding, with one legend stating that a Gimmighoul manipulated a girl to collect 999 coins to fill its chest. Its Roaming Form, meanwhile, is more timid in nature, being unable to manipulate people like its Chest Form, but instead can collect coins on its own. Despite both forms being available in Paldea, in the game lore no one has yet been able to catch the Roaming Form. Linking Pokémon Scarlet or Pokémon Violet with Pokémon GO, a feature slated to become available in 2023, will allow the player to catch Gimmighoul's Roaming Form in Pokémon GO. This Pokémon, and other Pokémon caught in Pokémon GO, will not be able to be transfered to Pokémon Scarlet or Pokémon Violet. Further details on how the connectivity between the games will work will be given at a later date.
This is not the first time Pokémon GO has teased a new Pokémon. Meltan was first teased during the Pokémon GO Community Day on September 22nd, 2018, before being officially revealed three days later.
Pokémon Scarlet and Pokémon Violet | Official WebsiteProfessor Willow and Mr. Jacq investigate a mysterious Pokémon in Pokémon Scarlet and Pokémon Violetscarletviolet.pokemon.com