Optional Bosses (Second Game)

Gutsy Bones
Encountering: Fought during the "Ghost Squad Part 3" Side Quest

Meganyan
Encountering:

Cap'n Crash
Encountering: Fought during the "Adventure Squad Episode 2-Seaside Specters" Side Quest

Eyeclone
Encountering: Fought during the "Whip up a Whirlwind" Side Quest

Goldy Bones
Encountering: Fought during the "Adventure Squad Episode 3-End of the Road" Side Quest