From the Super Mario Wiki
Koopaling Teamwork is a level in Dimble Wood in the Bowser Jr.'s Journey mode of Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey.
This level serves as a tutorial for First Officer commands. As such, when this level is first played, Bowser Jr. has no regular troops and Morton is the First Officer. As they approach the enemies, Morton teaches Bowser Jr. about his Shield command. After the level, Morton gives Bowser Jr. his Magic Paintbrush, allowing Bowser Jr. to be set as a ranged type.