Beat the Minions!
From the Super Mario Wiki, the Mario encyclopedia
Beat the Minions! is the final post-game level of the Bowser Jr.'s Journey mode of Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey, and by extension, the final level of the entire game.
Each round has a dark, Malatone Formula:X-infected Koopaling as the enemy captain, with all rounds but the first having a second dark Koopaling as first officer; they all use the same Captain Commands as their normal versions (apart from Ludwig's Negotiate; he uses Rally instead). The last round of the mission has all of the Koopalings as troops, with a dark and infected Bowser as the captain; he acts as a Melee-type unit and gives all the Koopalings Malatone Formula:X as soon as the battle starts. Almost every other enemy in this level is affected with Malatone Formula:X as well, apart from the three unrecruitable enemies at the back in rounds 1-4, as well as a Big Boo summoned by Larry's Call for Backup command in the fourth round.
After completing the level, Bowser Jr. and his troops will briefly celebrate while the game congratulates the player for completing the entire quest.