The official Pokémon Global Link website has announced that the
service will be unavailable from January 13, 2015 at 4am EST until January 15, 2015 at 11am EST. None of the services of the Pokémon Global Link, including Rating Battles or Game Sync, will be available during this time.
Source:
http://3ds.pokemon-gl.com/information/0532986b-ef8a-435c-ab75-a86a23158944