The Trio Clash!
From the Super Mario Wiki
The Trio Clash! is a level in Bowser's Castle (West) in the Bowser Jr.'s Journey mode of Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey. This level features the first battle against all three of the Best Fitness Friends. Alongside Koopaling Teamwork and Better Together, this level has a set troop when played for the first time.
Bowser Jr., Kamek, and the Koopalings discover that Bowser's Castle has returned to its original spot. However, the Best Fitness Friends get in the way, revealing that they have Wendy trapped in a barrel and threatening to throw her into the lava. The BFFs overpower Bowser Jr., but before they can finish him off, Captain Goomba, Captain Shy Guy, Captain Boo and Captain Koopa Troopa save him and free Wendy.
When this level is played for the first time, Bowser Jr. is set as a melee type, Ludwig is the First Officer, and the troops consist of Kamek and the four captains. As such, the music played before and during the level is the normal battle theme from Minion Quest: The Search for Bowser. After the level is completed, the four captains join the team.