Garlic Man
Name-change free since 2018
I don't remember which one was the hardest to accomplish for me, but the hardest to get a triple star rating was 5-4.
EDIT: 5-4 is the one where Bowser has to drive through the 10 gates in order in Bowser's Castle 2.
EDIT: 5-4 is the one where Bowser has to drive through the 10 gates in order in Bowser's Castle 2.