Rainbow Brite and the Star Stealer

Rainbow Brite and the Star Stealer is an animated film released on November 15, 1985 by Warner Bros., and produced by DIC Entertainment and Hallmark Cards. This is the only film to feature the greeting card character, Rainbow Brite she also appeared in a few television specials prior to its release, and later in a Kideo TV series.

When Rainbow Brite Bettina Bush and her magical horse, Starlite Andre Stojka, go to Earth to start spring, they meet Stormy Marissa Mendenhall, another magical girl who controls winter with her horse, Skydancer Peter Cullen. She, however, doesnt want to end her winter fun, so Rainbow battles her for control over the season. She proves to be no match for Rainbow and Starlite, who outrun her and head off to Earth. When they arrive, they meet up with Brian Scott Menville, the only boy on Earth who can see them.Once Rainbow tries to start spring, however, her power weakens and winter remains. Brian becomes worried that spring will never come and senses that all of humanity is losing hope. Even Stormy is confused. Reassuring Brian that they will do what they can to return spring, Rainbow and Starlite return to Rainbowland. ........

Source: Wikipedia