DeNA has announced that Zinnia & Rayquaza The Dragon That Rules the Sky will be available starting on December 13th, 2021 at 10:00 p.m. in Pokémon Masters EX.

Zinnia & Rayquaza The Dragon That Rules the Sky

You can complete the story to team up with Zinnia & Rayquaza! The Dragon That Rules the Sky has been added to Legendary Adventures, where you can team up with Zinnia & Rayquaza!

You can collect custom vouchers and Custom ★ Power-Ups by completing battles to increase Zinnia & Rayquaza’s potential and move level!

Date/Time Added

December 13, 2021 at 10:00 p.m.

Important

• The story is the same as the previously held Legendary Event: The Dragon That Rules the Sky.
  Note: You can claim the rewards even if you previously completed the Legendary Event: The Dragon That Rules the Sky.
• To participate in Legendary Adventures, you must have completed Main Story Chapter 1: The More the Merrier (Normal) in single-player.
• The Sync Pairs that appear as opponents in the Zinnia & Rayquaza: The Dragon That Rules the Sky battles have different capabilities than those you can actually obtain.
• Please note that if you fulfill the requirements to acquire Zinnia & Rayquaza after their Move Level has been upgraded to 5, you will get a 3★ Power-Up instead of a 5★ Power-Up.
• The content is subject to change without notice.

Source: https://pokemonmasters-game.com/en-US/announcements/Update_3110_3W_1