Meltan will always be unique - it's a new species of mythical Pokemon that made its debut in Pokemon Go rather than on a Nintendo-based Pokemon title. By using both Go and Let's Go, you can now catch Meltan and Shiny Meltan. Here's how.
The method of catching Meltan is the very definition of brand synergy - you'll need to enlist the help of both Pokemon Professors Oak and Willow - which means you'll need access to both Pokemon Let's Go for Nintendo Switch - either version is fine - and Pokemon Go on mobile. Willow will help you learn how to catch Meltan in Pokemon Go on mobile and once that's done, how it can then be transferred in order to then catch Meltan in Pokemon Let's Go Pikachu and Eevee games on Nintendo Switch. It sounds complicated, but it's not as winding as it sounds.
How to catch Meltan: the Mystery Box and transfers between Pokemon Go and Let's Go
Here's what you might have missed: Professor Oak has discovered a mysterious Metal Box that is made up of the same materials as Meltan itself - being that it is a Steel-type Pokemon that has liquid metal as a large part of its body. It's clear that this mysterious box is going to have a major impact on your ability to catch it.
It's all about that previously-mentioned cross-game synergy: players will be rewarded with a Mysterious Box the first time they transfer a Pokemon from Pokemon Go to Pokemon Let's Go. Subsequent transfers will get more standard rewards like Pokemon Candy, but the first time you transfer the Mystery Box is your in-game reward.
Opening the Mystery Box in Pokemon Go will then allow Meltan to appear for real in the game for a limited thirty minute period. These are real Meltan - not those Ditto-like appearances from earlier - and players can catch as many as spawn around them during the thirty-minute period after opening the Mystery Box.
Here's the good news - once you've retrieved the mystery box, it's yours forever. It'll remain closed for a week once opened, however, so you'll have to wait before opening it again, and each time you re-open it you'll need to sync up with Pokemon Let's Go. In essence, you get one week of Meltan catching time per week - and that's a challenge, given how much candy you're going to need for the creature to evolve.
Shiny Meltan and Evolution
A Shiny Meltan form also exists, though it only appears to spawn from the mystery box during certain special events. As with other Pokemon Go Shiny Pokemon, getting one to spawn is simply a matter of random chance and luck.
Once you've caught a Meltan in Pokemon Go, that same Meltan can then be transferred back to Pokemon Let's Go Pikachu and Eevee and caught once again over in those games. There is, however, an evolution - Melmetal. About that...
How to get Melmetal in Pokemon Go and Let's Go
In order to evolve Meltan to its much less cute, bruising-looking larger evolution, you'll need to do it in Pokemon Go: Meltan can't evolve in Pokemon Let's Go, only over in Go on mobile. To make it evolve you'll need to spend a huge 400 candy - so you're going to want to catch many, many Meltan, preferably using Pinap berries. Walking around with Meltan as your buddy Pokemon will help, too. Once evolved, you can send Melmetal back to Let's Go to complete that Pokedex if you want - but remember, it's a one-way, one-time deal.
In addition to all this, there's also a new series of Pokemon Go special research missions added to the game centered around the mystery of Meltan. These new missions exist in addition to the existing Mew and Celebi 'A Ripple in Time' quests.
It all seems a little complex, but The Pokemon Company and Niantic are clearly working hard to ensure players who are deeply involved in both Pokemon Go and Pokemon Let's Go are rewarded with access to this new Mythical Pokemon. Meltan and Melmetal's battle usefulness isn't fully clear yet - but generally speaking, Mythical Pokemon always chart well on our Pokemon Go Tier List of the best Pokemon - so we have high hopes.