The identity of the new Pokémon to possibly feature in Pokémon Let's Go was leaked during a Pokémon Go update and... it looks weird.
When Pokémon Let's Go Pikachu & Let's Go Eevee was first announced to the world, the release trailer had little to offer that hadn't already been leaked online. The fact that the game was a remake of Pokémon Yellow that had a Pokémon Go integration was known to the fans long before the official announcement took place.
One of the few revelations made during the initial trailer was that a brand new Pokémon would be appearing in Let's Go Pikachu & Let's Go Eevee, but its identity was kept a mystery.
The fan speculation about the identity of this Pokémon has been varied— there are some who think it might be the mythical Gorochu, who was revealed to be a scrapped evolution of Raichu in a recent interview with the creators of Pokémon Red & Blue. There was also speculation that it may be a new evolution for Eevee. The fact that Let's Go Pikachu & Let's Go Eevee is set in the Kanto region suggested that this Pokémon would be related to the original 151 Pokémon in some way.
It seems that the identity of the new Pokémon has been leaked during an update of Pokémon Go. Serebii is reporting that an unusual icon has been datamined by fans of the game which may be the new upcoming Pokémon. The update otherwise was adding data for Kecleon, one of the last Generation 3 Pokémon to come to Pokémon Go.
Potential spoiler for Pokémon Let's Go Pikachu & Let's Go Eevee incoming. You have been warned.
The creature in question looks like a ditto with a nut for a head, with one black orb in the center of the nut which may be an eye.
If this is the new Pokémon that is appearing in the game, then it's... weird. It's possible that it's related to Ditto, due to the resemblance between their bodies.
Pokémon Gold & Silver introduced the Metal Powder item to the series, which boosts the defense of a Ditto that is holding it. The leaked beta of Pokémon Gold & Silver revealed a bizarre looking metallic Ditto evolution, called Animon, which required trading with a Metal Coat in order to evolve, but this Pokémon never made it into the game.
Is it possible that this new sprite will be the metallic Ditto evolution that has been promised for so long, or is it some bizarre icon meant for something else? We will find out in November when Pokémon Let's Go Pikachu & Let's Go Eevee are released for the Nintendo Switch.