As of 1900 EST (Midnight GMT) on January 16th, 2017, Battle Spot Season 1 will be over. This coincides with the routine Pokémon Global Link maintenance for this week, and as soon as that is complete (around 2300 EST or 0400 GMT), Season 2 will begin.
Season 2 will run until March 19th, 2017 and battles will take place through Pokémon Sun and Moon.
The rules of the “Special Battle” format for Season 2 are a lot like those from Season 1. It allows one of the cover legendaries or Mythicals (or Mewtwo/Cosmog/Cosmoem/Phione) to be in your party.
Format: Single Battles
Pokémon Restrictions: National Pokédex.
Banned Pokémon: Only one of the following can be used per team: 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
The other standard rules apply, including all set to Level 50 if above that, and you choose 3 Pokémon out of your 6, and you cannot have two Pokémon holding the same hold item. Mega Evolutions and Primal Reversions are not specifically banned, but there is still no way to obtain Mega Stones for Pokémon not in the Alola Pokédex (that we know of).