If you made the rankings in the 2018 International Challenge January Online Competition, you can now claim your participation prize of 50 Battle Points now through March 30, 2018, at 23:59 UTC. Log in to the Pokémon Global Link (PGL) using the game that you used to participate in the 2018 International Challenge January and then click here. To redeem the code in your game, select Mystery Gift from the main menu, then select Receive Gift, select Get with Code/Password, and follow the prompts to enter your special code. Be sure to enter the code in your copy of Pokémon Ultra Sun or Pokémon Ultra Moon before March 30, 2018, at 23:59 UTC. Visit the Online Competitions page for 2018 International Challenge January Trainer and Pokémon rankings.
Source: Pokémon Global Link