Any review of Bowser's villain license would have him pass with flying colors. The man is a verbally-abusive, physically-violent, short-tempered planetary conqueror who loves showing his power with military parades, carving castles and warship figureheads into his own honor, and heaping glory onto himself. Any investigation into "teamed up with Mario to fight other villains" would uncover selfish reasons: said villains are out for mindless destruction, while Bowser considers the planets they are destroying his rightful property thank you very much

What is Dark Pit doing there? He's a goody two shoes who opposes the good guys all of two times, and that was basically because he was an angsty adolescent trying to establish an identity.