The official Pokémon website has announced the details for Ranked Battles Series 10 in Pokémon Sword and Pokémon Shield which begins on August 1st, 2021. Pokémon will not be allowed to Dynamax in this season but tough Legendary Pokémon usually not permitted in competitive matches are featured in this season.

Trainers Can Once Again Use a Restricted Pokémon in Ranked Battles Series 10, Starting August 1, 2021

Choose wisely and play hard in Pokémon Sword and Pokémon Shield with the latest Ranked Battles Series.

Ranked Battles Series 10 begins on August 1, 2021, in Pokémon Sword and Pokémon Shield, and with it comes another chance to battle together with tough Legendary Pokémon usually not permitted in competitive matches. As previously seen in Ranked Battles Series 8, Trainers can include one Pokémon from the Restricted Pokémon list below on their Battle Team. Note that this is different from previous GS Cup regulations where two of these Pokémon were permitted on a Battle Team.

As an added twist to the Series 10 regulations, Pokémon will not be allowed to Dynamax!

Eligible Pokémon

Mewtwo, Lugia, Ho-Oh, Kyogre, Groudon, Rayquaza, Dialga, Palkia, Giratina, Reshiram, Zekrom, Kyurem, Xerneas, Yveltal, Zygarde, Cosmog, Cosmoem, Solgaleo, Lunala, Necrozma, Zacian, Zamazenta, Eternatus, Calyrex

• Mythical Pokémon are not permitted in battle.
• All other Pokémon from the Galar Pokédex, the Isle of Armor Pokédex, and the Crown Tundra Pokédex as well as certain other Pokémon are permitted.
• Only Pokémon obtained in Pokémon Sword or Pokémon Shield or those with the battle-ready symbol are eligible.
• Pokémon will not be allowed to Dynamax.
• All Pokémon will be set to Lv. 50, including Pokémon below Lv. 50.
• Duplicate Pokémon are not allowed.
• Duplicate held items are not allowed.

Timer Regulations

• Each battle begins with a 90-second Team Preview phase.
• In each battle, players have the following time limits:
• 7 minutes of Your Time
• 45 seconds of Move Time
• 20 minutes of Game Time

Good luck battling in Pokémon Ranked Battles Series 10 starting August 1

Source: https://www.pokemon.com/us/pokemon-news/trainers-can-once-again-use-a-restricted-pokemon-in-ranked-battles-series-10-starting-august-1-2021/