The producer of Pokémon Masters Yu Sasaki posted an open letter about the game on the Pokémon Master's official website. The letter addresses the upcoming changes to the game.

A Message from the Pokémon Masters EX Team (Vol. 45)

Greetings, Trainers.
We’re the producers of Pokémon Masters EX, Yu Sasaki and Tetsuya Iguchi, here with a new message for you. Today, we’ll focus on details about events beginning around the end of March and the new Sync Pairs that will debut.

App Update for Late March - A New Guest Arrives in the Trainer Lodge

Starting March 30, 2023, you’ll be able to invite Steven as a Guest to the Trainer Lodge! To invite Steven, you’ll need to team up with Steven & Metagross first. Steven & Metagross will be featured in the Monthly Poké Fair Scout Vol. 8, which will be available the next day, so you can team up with them if you haven’t yet. Steven & Metagross will also get tiles for Fair-Exclusive Sync Pairs in this update, so be sure to check them out.

Raising Sync Pairs to 6★ EX without EX Style

In order to give even more Sync Pairs a chance to shine, the next update will introduce the ability to unlock 6★ EX without an EX Style. In the future, some Sync Pairs may gain the ability to be raised to 6★ EX without getting an EX Style. To coincide with the next update, some Sync Pairs that cannot currently be raised to 6★ EX will gain the ability to be raised to 6★ EX without getting an EX Style.

Costume Event Solve the Mystery Case! (Part 1) Is Coming!

Costume Event Solve the Mystery Case! (Part 1) will begin on March 30, 2023. Steven and other Trainers are participating in a mystery game held by Lear. Will they be able to play their roles in the game and figure out who the culprit is?

This Costume Event comes in two parts. The second part is scheduled for mid-April, so we hope you look forward to it! This Costume Event will also feature four Sync Pairs in special costumes connected to the event’s story. Next, we’d like to show you the two Sync Pairs that will arrive in the first part of the event.

Steven (Special Costume) & Stoutland

Steven (Special Costume) & Stoutland are a Normal-type tech Sync Pair that can weaken opponents and power up allies. With their Passive Skill, they can lower the target’s Type Rebuff of its weakness type by one rank the first time they successfully use an attack move each battle.

Also, they can use their B Leer Buddy Move when a Type Rebuff of any opponent has been lowered.This Buddy Move lowers the Attack, Defense, and Speed of all opponents by two stat ranks.

In addition, they have ways to support the firepower of their allies, such as with Super Effective ↑, which applies the Supereffective ↑ Next effect to one ally, and Mystery Solved!, which raises the Physical Moves ↑ Next effect of one ally by three ranks.

You’ll be able to view a special Friend Snapshot in the Trainer Lodge by teaming up with Steven (Special Costume) & Stoutland, so be sure to check it out.

Shauna (Special Costume) & Klefki

Shauna (Special Costume) & Klefki are a Steel-type support Sync Pair that can raise allies’ stats and lower the opponent’s.

When they successfully attack with a move, their Passive Skill randomly lowers one of the target’s following stats by one stat rank: Attack, Defense, Sp. Atk, Sp. Def, or Speed. It then raises that stat for all allies by the same amount.

Plus, when they get hit by an attack move, they can randomly lower one of the following stats of the opponent that attacked them by one stat rank at random: Attack, Defense, Sp. Atk, Sp. Def, or Speed—then raise their own stat by the same amount.

I Think I’ve Got It! applies the Status Move Defense and Stat Reduction Defense effects to the allied field of play and raises the critical-hit rate of all allies by two stat ranks.

Improvements to the Champion Stadium - Option Additions to Master Mode

New Options will be added to Master Mode of the Champion Stadium starting with the Kanto Challenge beginning on April 2, 2023. To coincide with this, the maximum number of points that can be earned in a single battle has been raised to 2,500, bringing the final total number of points to 12,500. We hope you do your best as you aim for a high score.

We’re also planning a feature that lets you save and load the Options you select for next month’s update, so we hope you look forward to it.

Limited-Time Champion Stadium Event

A limited-time Champion Stadium event titled Pasio Special Stadium will begin on April 10, 2023. It will be different from—and run concurrently to—the Champion Stadium that has been available. Unlike the usual Champion Stadium, a mix of Elite Four members and Champions from different regions will be your opponents in this event. A certain type will be effective in this event’s battles, and a special Sync Pair is planned to make an appearance as a Champion, so please wait a little longer for this event.

New Event: Trainer Files Is Coming!

A new event titled Trainer Files is scheduled to begin in late April. Certain Trainers will get the spotlight in Trainer Files, letting you enjoy mini stories featuring them.

This time, the event will focus on the Kanto Elite Four. We plan to hold this event occasionally in the future, so we hope you look forward to future events focused on different regions and Trainers!

Other Events and Updates

A variety of other events and updates are scheduled as well, including Special Event Helping Out on Pasio, which features Missions that—unlike regular Missions—do not give you specific requirements to complete. Also, the sixth part of the Paulo Interlude will be added to the Villain Arc, and Story Event Pasio Eggsplorers will return.

Future Updates

We’re planning features for the next update, including one that lets you save and load your Option settings for the Champion Stadium’s Master Mode, so we hope you look forward to it!

What to Expect in the Next Message

Our next message is scheduled for late April. In it, we plan to share information about new Sync Pairs and events for May.

We’re always working hard to deliver updates and improvements that make the world of Pokémon Masters EX as fun as possible.

Until next time, thank you for playing Pokémon Masters EX.

Pokémon Masters Producer: Yu Sasaki
Operations Producer: Tetsuya Iguchi

Source: https://pokemonmasters-game.com/en-US/announcements/Other_5020_5W_1