The new trailer shows off Meltan's evolved form, Melmetal who is a steel type Pokémon. The press release also revealed that Meltan can only be evolved in Pokémon GO and requires you to have 400 Meltan candy. So trainers wishing to train a Meltan in Pokémon: Let's Go, Eevee! or Pokémon Let's Go, Pikachu! won't be able to evolve it in game, they'd have to first evolve it into Melmetal in Pokémon GO and then trade that across.
Details of the Pokémon are as follows:
Category: Hex Nut Pokémon
Height: 2.5m / 8’02”
Weight: 1,763.7 lbs.
Melmetal was worshiped in ancient times as a Pokémon with the power to create metal. Because of its Evolution from Meltan, its body has hardened and is now incredibly sturdy.
Melmetal is made of liquid metal, and its flexible arms can be whipped forward to deliver a devastating punch. It can also execute a powerful, unique Steel-type physical move known as Double Iron Bash. By using the hex nut in its chest like an axle to spin its arms around, Melmetal can deal a double strike to its opponent. The weight of the heavy hex nuts on its arms combined with the spinning motion gives the Double Iron Bash move extraordinary power.