Like Father, Like Son

Like Father, Like Son is the final level of the story mode in the Bowser Jr.'s Journey mode of Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey, and involves the final battle with the Best Fitness Friends

Overview
After Bowser Jr. and the Koopalings reach the Best Fitness Friends, Dieter questions Bowser Jr. on whether or not Bowser and his minions are evil, which Bowser Jr. denies, stating "good and evil are outdated". The final battle then commences, first fighting the group at once, then they all take Malatone Formula:X and are each defeated a few more times. After their defeat on round four, they merge together into one giant horrifying monster, using dark doppelgangers of the Koopalings as its troops.

This level is unique for having two themes. The normal boss theme plays for rounds one to four, then for round five a new theme exclusive to this battle plays.