Boo Brigade is a level in Bowser's Castle (East) in the Bowser Jr.'s Journey mode of Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey.
As Bowser Jr. has passed Captain Shy Guy, he encounters Captain Boo, who was waiting for him. Before the battle starts, Morton steps onto the scene to teach Bowser Jr. on how to pause using the button to check the length of the battle. Bowser Jr. replies to Morton that he was a big fan of the button and that he got it. He then asks him if that was it. Morton claims that he is done explaining. After the battle, Morton hands Bowser Jr. a drumstick, which happened to be all burnt up. Morton comments to Bowser Jr. that he cooked the Drumstick with fire, and that fire is strong enough to cook it greatly. Bowser Jr. replies that he'll eat it later. Ludwig, watching the conversation, tells Roy that Morton was smarter than he looked and that he was trying his best to be courteous with Bowser Jr. Roy tells Ludwig that he wanted to go home and that he isn't one "babysitting" Bowser Jr. Ludwig tells Roy that even though he was acting selfish, the quest to find the ingredients for the Skeletone was working and they head off to teach Bowser Jr. the next lesson.