From Bulbanews, your community Pokémon newspaper.
Only Eevee, Pikachu can be used
The Let's Go Cup competition has been announced. This competition will us the Single Battles format, where only Pikachu and Eevee may be used. Players may register between midnight UTC on July 26 and 11:59 p.m. UTC on Aug. 2. The tournament will run from midnight UTC on Aug. 3 until 11:59 p.m. UTC on Aug. 5. The results will be announced some time in August. Participants that win or lose one battle will receive a mobile-sized wallpaper that features the Pokémon that was used the most during the competition.
Pokémon Ultra Sun and Ultra Moon must be used for the competition. Eevee and Pikachu brought over from previous generations may be used. Only one Pokémon may be registered in the Battle Box and used in the competition. Items may be used, and are not being restricted. All Pokémon will be automatically set to level 50. Each battle will last a maximum of 5 minutes. Players will have 30 seconds to select a move to use. Participants can battle 10 times a day for a maximum of 30 battles.