Quote:Players can also transfer the original first-generation Pokémon and their respective Alolan forms from Pokémon Go to Let's Go, Pikachu! or Let's Go, Eevee!. They will then appear at the Go Park; an in-game location that the player can explore where they can interact or catch Pokémon that are walking around, although Pokémon with higher CP or levels are harder to catch, in that the catch attempt has a higher chance of failing. Users will also be able to exchange unspecified "gifts" between Pokémon Go and Let's Go, Pikachu! or Let's Go, Eevee!.

The Pokemon Company Wrote:

Meltan is a Steel-type Pokémon with a body made mostly of liquid metal, which makes its shape very fluid. This Pokémon can use its liquid arms and legs to corrode metal and absorb it into its body. Meltan can generate electricity using the metal it absorbs from outside sources. It uses this electricity as an energy source and for an attack it fires from its eye.

Name: Meltan
Category: Hex Nut Pokémon
Height: 0’08”
Weight: 17.6 lbs.
Type: Steel

In Pokémon GO, sightings of Ditto that have transformed into Meltan have been reported. Professor Oak and Professor Willow have started research on Meltan. Professor Oak, one of the leading authorities in the field of Pokémon research, is based in the Kanto region’s Pallet Town. In Pokémon: Let’s Go, Pikachu! and Pokémon: Let’s Go, Eevee!, he gives a Pokédex to both you and your rival—entrusting you with his dream of completing it. Meanwhile, with the help of Pokémon GO players around the world, Professor Willow conducts his research in the field to fully understand the habitats and distribution of Pokémon. He was once an assistant to Professor Oak, and he talks to Oak, his mentor, whenever he runs into a hitch in his research.

It has been determined that Pokémon GO is somehow key to meeting Meltan in Pokémon: Let’s Go, Pikachu! and Pokémon: Let’s Go, Eevee! Updates will be provided as more is discovered about this mysterious Mythical Pokémon.