Thinking of 2-D platforming powers is fun. Sadly I only thought of two good ones so far. Although they're probably not unique but I just need to think of things for a class project.
Make a power that changes the landscape from day to night at will... or something that alters the level idk. Make a power up that changes it to 3d, and yet it's still actually 2d. It's your job to make it work.
So far I thought of, the power to alter the character's gravity, and the power to light up the area because there will be some spots that will be some dark areas.