I watched an anime (not sure if it was a movie or t.v. show) years ago, and it was about a girl who gained powers. It was weird in the sense that the powers that were passed on to her, or granted to her, were previously held by a boy in a wheelchair.
I remember that the boy was very unlikable and rude. He came to the girl in a helicopter or an airplane/jet. He tries to guide the girl in how to use her power, but she uses her power to attack monstrous creatures. That angers the boy. The boy explains that the creatures aren't the real problem, and it was the pollution that created them in the first place. He seems disappointed that she would attack before trying to understand what was happening.
The boy also seems to be getting weaker throughout the anime, almost as if he were dying because the power that is being transferred to the girl is killing him? The power passed on had something to do with being in tune with nature, or cleansing the natural world from pollution. I'm not 100% sure.