Updated story (November 17th): Meltan is now available for Pokémon Go players without having to own the newly released Pokémon Let's Go on Nintendo Switch as part of a new quest.
But by the end, the chance to own Meltan without access to Let's Go is yours. You can see exactly what you need to do in our Pokémon Let's Go Meltan quest steps page.
Of course, if you want to get its evolution Melmetal - and the huge amount of Candy it requires - then seeking out a copy of Let's Go on Switch is your best bet.
The quest was joined by a several Kanto-themed quests to celebrate the arrival of Let's Go - which, apart from Meltan, is based entirely on the franchise's initial set of 151 creatures - but not without a hitch, displaying placeholder text for all players for around an hour after it went live.
Guess that's one way to keep things from leaking ahead of time, right?
Cheers pal pic.twitter.com/8dX9RmmVm1— Matthew Reynolds (@Crazyreyn) November 16, 2018
Original Story (November 15th): Classic Pokémon such as Magmar and Electabuzz can now evolve for the first time in Pokémon Go.
Last night, Pokémon Go added a new item which unlocks these species' new Gen 4 evolutions. Named the Sinnoh Stone, after the Gen 4 games' region, this one-size-fits-all item replaces some complicated mechanics found in the original Diamond and Pearl games.
Half of the 22 Pokémon to gain new evolutions in Gen 4 can now evolve using the item. I'll save the full details for Eurogamer's Pokémon Go Sinnoh Stone guide, but the following species are now evolvable: Rhydon, Electabuzz, Magmar, Togetic, Misdreavus, Murkrow, Gligar, Sneasel, Porygon 2, Roselia and Dusclops.
The other 11 evolutions will presumably be released at a later date, although it will be a while before you can get all of those. Sinnoh Stones are currently very rare - only obtainable via a seven-day Field Research Task reward. At one Stone per week, it'll be January before you have every evolution.
But other methods to gain Sinnoh Stones will be available at a later date, Niantic community manager Liz George told Silph Road. Hopefully they'll be added to your weekly 50km Adventure Sync rewards, which are currently rather underwhelming.
Mythical Pokémon Meltan - aka Nutboy - has already been obtained by players with early copies of Pokémon Let's Go Pikachu and Eevee. Images posted to Silph Road show the Pokémon Go to Switch connectivity is up and running. Transfer a Pokémon from Go to Let's Go and you'll get an item which lures Meltan to your Pokémon Go game.
And finally, there's a new Pokémon Go egg event, with some of the newly-evolvable species added to 2km eggs and shiny Elekid released for the first time.