If you’ve made it all the way to Fuschia City and started transferring Pokemon from Pokemon GO to Let’s Go then you have certainly received the Mystery Box. This special item is the reward for connecting your games together, and it’s a very important item for your future with both titles. But unless you’re ready to activate it without any idea what it does you might be wondering what does the mystery box do in Pokemon GO and Pokemon Let’s Go Pikachu and Eevee.
The answer is actually pretty simple, though the usual special Niantic twist is there to make sure it’s not all that simple. In short, the mystery box makes Meltan spawn around you for thirty minutes. You can open the mystery box once per week, giving you thirty minutes a week to catch this very special and rare mythical Pokemon. Yes, that does mean you will want to make sure you open the Mystery Box when you’re ready to catch all the Meltan you can.
Meltan is very tough to get to get in either PoGo or Pokemon Let’s Go, as we break down here. The key is to get him in GO as much as possible, including the research quest that you should have active now. Finish that to catch one Meltan, which you can add to with your Mystery Box catches. Once you have enough you can evolve him into Melmetal and transfer some over to Pokemon Let’s Go Pikachu and Eevee.