Registration for the 2017 International Challenge May has officially concluded, which means you can now begin battling as part of the latest Online Competition in Pokémon Sun and Moon. Registered competitors can battle up to 15 times per day until the competition concludes on Sunday, May 28, 2017, at 23:59 UTC. Championship Points toward an invitation to the 2017 Pokémon Video Game World Championships are on the line in this global competition. Plus, all qualified participants will earn Tyranitarite, Abomasite and Manectite Mega Stones. This competition uses the same rules and regulations as Pokémon Video Game Championship Series events.
If you missed the chance to register and battle in this competition, be sure to keep checking the Pokémon Global Link (PGL) for more opportunities to battle in the future.
Source: Pokémon Global Link