A, here is how to get Mewtwo via the Project M side mission and use a Mystery Gift to get the Mewtwonite X & Y Mega Stones.

If you want to add the classic legendary Pokemon that is Mewtwo to your party in Pokemon Legends: Z-A, you’ll have to do more ...

The Master Ball comes from Mable's Research. The NPC herself can be found in the Pokemon Research Center in the southern part of the map. You can't miss it since a main quest takes you there fairly ...