Head into the Pokemon GO Park Complex in Fuschia City and talk to the attendant
Select ‘Bring Pokemon’ from the menu
IN POKEMON GO (APP)
Open Pokemon GO and tap the Pokemon icon
You can then tap the Nintendo Switch icon in the top right corner
You will have to choose each Pokemon that you want to send (Kanto and Alolan forms only)
Tap send to Nintendo Switch to send all of your Pokemon to a Pokemon GO Park (These Pokemon will no longer be in Pokemon GO)
HOW TO GET MELTAN IN POKEMON GO
In order to get Meltan in Pokemon GO, you’ll need to transfer any Pokemon into the Pokemon Let’s GO Park (from Pokemon GO).
You’ll then get a ‘Mystery Box’ which will transfer through to your Pokemon GO account. Once you open this (and this is very important), you’ll get to catch Meltan for 30 minutes. He will appear every 3 minutes and once this 30 minute time limit is over, you’ll need to wait another 7 days (a whole week) before you can re-open the Mystery Box (by transferring another Pokemon from Pokemon GO to Pokemon Let’s GO).
You can then transfer Meltan to Pokemon Let’s GO by following the above steps again and then by catching him in the Pokemon GO park (to use in your party).
HOW TO EVOLVE MELMETAL IN POKEMON GO
This is where it gets even more interesting. You can only evolve Melmetal in Pokemon GO, so you’ll need to keep at least one Meltan in your Pokemon GO account (as you can’t transfer it back).
It’s going to be a difficult time to evolve Meltan into Melmetal as you need 400 Meltan candys in order to evolve him. Judging by the limit of only having 30 minutes Meltan catching item per week, you’re looking at roughly 6-7 weeks without speeding it up..
Here’s some tips that Nintendo has provided for evolving Meltan to Melmetal:
Just as with the Candies you collect for other Pokémon, you’ll be able to get Meltan Candies by doing things like catching Meltan, sending it to Professor Willow, or having Meltan travel around with you as your Buddy Pokémon.
You’ll also get these Candies when you send Meltan from Pokémon GO to Pokémon: Let’s Go, Pikachu! and Pokémon: Let’s Go, Eevee! Plus, you’ll also be able to use some other handy shortcuts to speed up this Evolution, such as getting more Meltan Candies by trading with friends or using Rare Candies to help you along the way.