At the 2018 Pokémon World Championships, the first details of the 2019 Video Game Championships formats were revealed. 2019 Video Game Championships will include the following rules listed below.

Get Ready for a Legendary Video Game Championships Season!

Check out the full details of the new 2019 Video Game Championships formats.

Major changes are on the way that will make the Video Game Championships more exciting than ever for the 2019 Championship Series season. Battles will be shifting to the GS Cup battling format starting on September 4, 2018, so players will need to devise new strategies as soon as the 2018 Pokémon World Championships ends. Last seen during the 2016 Video Game Championships, this popular format permits players to include up to two of the most powerful Legendary Pokémon on their teams, such as Mewtwo, Groudon, and Necrozma.

Battles in this year's Video Game Championships will stay fresh due to additional rules that will change throughout the season. The 2019 Video Game Championships will be split up into three series, each featuring a slightly different rule set. The season will kick off with the Sun Series, followed by the Moon Series and then the Ultra Series. In the Sun Series, not only will Rayquaza not be permitted to use Dragon Ascent, but also the Red Orb and Blue Orb items and all Z-Crystals and Mega Stones will be prohibited. Players will be able to test out their strategies as soon as the Sun Series begins on September 4, 2018, by competing in Rating Battles using the Championships Battle format on the Pokémon Global Link.

All tournaments that are part of the 2019 Video Game Championships will include the following rules.

• All battles will be Double Battles played in Pokémon Ultra Sun and Pokémon Ultra Moon.
• All Pokémon from National Pokédex No. 001 through 807 are allowed, with the following restrictions:
  • Mythical Pokémon and Ash-Greninja are not permitted.
  • Players may only include two of the following Pokémon in their teams: Mewtwo, Lugia, Ho-Oh, Kyogre, Groudon, Rayquaza, Dialga, Palkia, Giratina, Reshiram, Zekrom, Kyurem, Xerneas, Yveltal, Zygarde, Cosmog, Cosmoem, Solgaleo, Lunala, Necrozma.
• Pokémon must have the Alola symbol, showing they were caught in the Alola region.
• Duplicate Pokémon are not allowed.
• Duplicate held items are not allowed.
• All Pokémon are set to Lv. 50, including Pokémon below Lv. 50.
• Players will have 7 minutes of Your Time, up from 5 minutes in 2018.

The following additional rules will be in place only during their respective series.

Sun Series
September 4, 2018–January 7, 2019

• Z-Crystals and Mega Stones are not permitted.
• Blue Orb and Red Orb items are not permitted.
• Rayquaza may not know the move Dragon Ascent.

Moon Series
January 8, 2019–April 1, 2019

• Ultranecrozium Z is not permitted, but other Z-Crystals are permitted.
• Mega Stones are not permitted.
• Blue Orb and Red Orb items are not permitted.
• Rayquaza may not know the move Dragon Ascent.

Ultra Series
April 2, 2019–Pokémon World Championships in August 2019

• All moves and items obtainable through normal gameplay are permitted.

Get ready for unbelievable battles with the new 2019 Video Game Championships format starting on September 4, 2018.

Source: https://www.pokemon.com/us/pokemon-news/get-ready-for-a-legendary-video-game-championships-season/