>>37344365Once a week when you send Pokemon over you can open the Meltan Box. It works like a lure to get Meltan to appear around you for 30 minutes. Generally if you move around and keep catching them quickly you can usually get around 20 to spawn (that's about 60 candy). If you use pinap or silver pinap berries you'll get double that.
A few weeks ago with the double candy event I was able to get one, but you'll most likely have to do the Meltan catching for at least a few months.
Its a tough Pokemon to get but its got retard strength against anything thats weak to it in Go. I used it in a gym battle and it basically rinsed everything in the gym i was at.