The Pokémon Global Link is currently undergoing maintenance. If you try to use it, it will fail.
The maintenance started at midnight November 10 2017, and it will last until midnight 17 November 2017 (UTC). The Pokémon Company International has taken it offline to update it for the official release of Pokémon Ultra Sun and Pokémon Ultra Moon.
It seems that after the update it will work with both Pokémon Ultra Sun and Pokémon Ultra Moon, as well as with Pokémon Sun and Pokémon Moon. Right now the Global Link features won't work for either Pokémon Sun and Pokémon Moon, this includes Game Sync as well as Rating Battles.
After the maintenance is done, the new games will officially be released, in the meantime be sure to stay offline or else you will more than likely get banned like last year.
Young children should read this with an adult.
During maintenance, all Pokémon Global Link services are unavailable. Please try accessing the site again after maintenance is complete.
・All services on the Pokémon Global Link website
・Features related to Pokémon Sun and Pokémon Moon, including
- Game Sync
- Rating Battles
Maintenance and periods of unavailability
From midnight, Nov. 10, 2017, to Nov. 17, 2017 (UTC)
Note: Completion times are subject to change.
If you see this screen at a time other than during the maintenance period described, the site is undergoing emergency maintenance.