Board Thread:Tapped Out Help/@comment-24.14.191.60-20140830021021/@comment-25363517-20140830212431

Bart is easier:

Goblin Bart  is a costume for Bart Simpson released on August 19, 2014, as the fourth prize for the Clash of Clones 2014 Event.

He is unlocked upon completion of Boxingham Palace.

Marge takes a while:

Wizard Marge  is a costume for Marge Simpson released on August 19 2014, as the fifth prize for the Clash of Clones 2014 Event.

Players must complete the Prince and the Premise Pt. 17 to unlock Wizard Marge.