The Pokémon Global Link website has announced the details for Rating Battle Season 6 for Pokémon Sun or Pokémon Moon.

Rating Battle Season 6

It’s that time again! The new Rating Battle Season 6 is upon us! Put your Pokémon Trainer skills to the test as you compete in ranked online matches with players from around the world. The leaderboards are reset each Rating Battle Season, so everyone starts on equal footing. As you battle, you’ll move up and down the rankings based on your match outcomes. Rating Battle Season 6 runs from September 12 through November 14, 2017, so get in there and start battling!

Eligible Pokémon for Rating Battle Season 6 include Pokémon from the National Pokédex No. 001–802. However, this season’s Special Battles rules feature only Pokémon that haven’t ranked in the top 15 at the end of Single Battle Seasons 2–4. Additionally, all Pokémon that ranked in top 15 of the Pokémon ranking as of August 3 (during Single Battle Season 5) cannot be used. These Pokémon include Charizard, Gengar, Gyarados, Porygon2, Blaziken, Salamence, Garchomp, Lucario, Hippowdon, Mamoswine, Ferrothorn, Landorus, Greninja, Aegislash, Mimikyu, Tapu Koko, Tapu Lele, and Tapu Fini.

Other Pokémon that are not permitted in Rating Battle Season 6 are Mewtwo, Mew, Lugia, Ho-Oh, Celebi, Kyogre, Groudon, Rayquaza, Jirachi, Deoxys, Dialga, Palkia, Giratina, Phione, Manaphy, Darkrai, Shaymin, Arceus, Victini, Reshiram, Zekrom, Kyurem, Keldeo, Meloetta, Genesect, Xerneas, Yveltal, Zygarde, Diancie, Hoopa, Volcanion, Cosmog, Cosmoem, Solgaleo, Lunala, Necrozma, Magearna, Marshadow, and Ash-Greninja.

Source: https://3ds.pokemon-gl.com/information/c05e9ef6-d9fd-4a20-b926-7b81a3350277