From the Super Mario Wiki, the Mario encyclopedia
The Side Somersault (referred to as Side-flip by Prima Game Guides) is a high jump that debuted in Super Mario 64 which typically grants a small amount more height than the Backwards Somersault. It is useful when the player wants to immediately jump high to reach high ledges. To use it, the character must run in one direction, then simultaneously turn to run in the other direction and jump.
In Super Mario Sunshine, Mario only needs to face in one direction and turn around; therefore, Mario could execute a Side Somersault with almost no space to move.
In Super Mario Galaxy 2, Yoshi can also Side Somersault.
Super Mario Sunshine
Super Mario 3D Land
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