#113 - Peach in 3D World

Super Mario 3D World is the only 3D Mario platformer where Peach doesn't need to be rescued. However, this was still the first idea for the story, but was scrapped as producer Yoshiaki Koizumi thought it would be fun to have her as a playable character.

SOURCE: https://www.polygon.com/2013/6/12/4421244/nintendo-thinking-on-a-different-frequency-with-playable-princess