A maintenance period for the Pokémon Global Link will take place mid November 2014. This is separate to the Code Redemption downtime previously announced for Pokémon X and Pokémon Y. This maintenance period will be for getting ready for the launch of Pokémon Omega Ruby and Pokémon Alpha Sapphire. Due to this maintenance, the end date of Rating Battle Season 6 which was previously November 20th, 2014 has now been changed to November 13th, 2014 at 3:59 a.m. (EST). The date will be modified during the regularly scheduled maintenance period on October 20th, 2014. The ORAS extended maintenance period is for the following days:

For the United States: November 13th, 2014 at 4:00 a.m. (ET) until November 21st, 2014
For the United Kingdom: November 13th, 2014 at 9:00 a.m. until November 21st, 2014.

Source: http://3ds.pokemon-gl.com/information/a72e009b-84e6-459a-9d44-3ae5e2412963