DeNA has announced that the Legendary Arena Cresselia and the Lysandre Poké Fair Scout will take place from August 19th, 2021 at 11:00 p.m. until September 3rd, 2021 at 10:59 p.m. in Pokémon Masters EX.

Legendary Arena Cresselia

Legendary Arena: Cresselia is back! Starting today, Legendary Arena: Cresselia returns! New Event Missions have been added along with its return! You can complete higher difficulty missions to get Gems!

Date/Time

August 19, 2021 at 11:00 p.m. - September 3, 2021 at 10:59 p.m.

Legendary Arena

The Legendary Arena is a special battle area where you can form multiple teams and take on the challenge using a set number of sync pairs. You can complete the related missions to earn Medals that can only be obtained here!

Important

• To attempt Legendary Arena missions, you must have completed Main Story Chapter 2: Defeat Team Break! (Normal) in single-player.
• Your area info and mission completion data will be saved at the event’s conclusion and will be used the next time this event returns.
• While Legendary Arena missions will also be displayed on the General missions screen, they cannot be attempted outside of the challenge period.
• The event missions held at the same time as the Legendary Arena do not count toward the completion requirements for Legendary Arena Mission Completion Rewards.
• All completion rewards for event missions held at the same time as the Legendary Arena must be claimed within three days of the mission period ending.
• The time period and featured content are subject to change without notice.

Source: https://pokemonmasters-game.com/en-US/announcements/Event_3070_4W_4

Lysandre Poké Fair Scout

Team up with a fair-exclusive sync pair in the Poké Fair Scout now! 5★ Lysandre & Yveltal are being featured in this limited-time Poké Fair Scout! 5★ sync pairs have a 10% chance of appearing in the Poké Fair Scout! Don’t miss this chance to team up with this fair-exclusive sync pair!

About Lysandre & Yveltal

The boss of Team Flare uses powerful Flying- and Dark-type moves and can even restore HP!

Date/Time

August 19, 2021 at 11:00 p.m. - September 3, 2021 at 10:59 p.m.

Important

• 5★ Lysandre & Yveltal are a fair-exclusive sync pair.
• Fair-exclusive sync pairs are sync pairs that will appear for a limited time during this Poké Fair Scout.
• There is a possibility that they will appear in other Poké Fair Scouts in the future as well.
• Sync pairs other than the ones mentioned above may also appear in the Poké Fair Scout.
• To unlock the sync grid, you must have completed Main Story Chapter 2: A Friendly New Rival (Normal) in single-player.
• Please note that you cannot have two or more sync pairs that include Trainers with the same name in your team.
• Featured sync pairs have a higher chance of appearing than non-featured 5★ sync pairs.
• The number of times the daily discount (100 paid Gems per scout) can be used is reset each day. Reset Time: 11:00 p.m.
• To check the available sync pairs and their respective offering rates, go to the Offering Rate section on the Sync Pair Scout screen.
• Please read the Notes section under Offering Rate on the Sync Pair Scout screen before using the feature.
• The time period and featured content are subject to change without notice.

Source: https://pokemonmasters-game.com/en-US/announcements/BSearch_3070_4W_1