The official Pokémon Global Link website has announced that those that register or use Game Sync with Pokémon Ultra Sun or Pokémon Ultra Moon between November 17th, 2017 and January 30th, 2018 will receive a free Master Ball.

Receive a Master Ball!

It’s one of the rarest and most valuable items in the world of Pokémon—a special Poké Ball that will catch any Pokémon in one shot 100 percent of the time. Even Legendary Pokémon are no match for it. We speak, of course, of the mighty Master Ball, coveted by Pokémon Trainers everywhere as a surefire way to add an elusive Pokémon to their Pokédex.

Can’t believe we’re just giving away Master Balls?! It’s true! Trainers who register and use Game Sync to connect their copies of Pokémon Ultra Sun or Pokémon Ultra Moon with the Pokémon Global Link between November 17, 2017, and January 30, 2018, will receive a free Master Ball as an introductory bonus. And yes—if you own both Pokémon Ultra Sun and Pokémon Ultra Moon, you’ll be able to score a Master Ball for each game!

Click here for directions on how to register your game and use Game Sync to connect with the Pokémon Global Link. If you register and then use Game Sync during the eligible time window, a link will be provided toward the end of January 2018 with instructions on how to claim your Master Ball.

So which Pokémon will you catch with your Master Ball? Start thinking about it now, and remember to perform Game Sync with the PGL once you have your games, whether Pokémon Ultra Sun or Pokémon Ultra Moon—or both!

Source: https://3ds.pokemon-gl.com/information/60c5ca2f-d4e2-460c-a728-5b21d18ffb0d