More information on Meltan revealed

A second video in The Two Professors series has been released. Professor Oak informs Willow about a Mystery Box that is key to encountering Meltan.

It has been confirmed that both Pokémon GO and Pokémon Let's Go Pikachu/Eevee are required for capturing Meltan. The first time a Pokémon is sent from GO to Let's Go, the player will receive the Mystery Box. When the box is opened in Pokémon GO, Meltan will begin appearing and can be caught like other Pokémon. Then it can be sent back to Pokémon Let's Go Pikachu/Eevee.

A second live-action trailer featuring Meltan was also released:

The end of the trailer promises a bigger secret to be uncovered. Several Meltan are seen cozying up together but then a large shadow looms.