It's not unusual for a Dragon Ball Z villain’s scariest and most creatively designed form to be a middle stage transformation ...
A new transformation is the easiest and most effective shorthand to convey that someone is more powerful, which is why villains like Frieza, Cell, and Buu have all returned with new forms.
Son Goku typically defends the Earth from villains like Vegeta, Frieza, Cell, and Majin Buu. The series is followed by Dragon Ball GT and then Dragon Ball Super.
Majin Buu is one of the series' most powerful characters, but here's how he continues to be wasted in the Dragon Ball franchise!