Rainbow Brite and the Star Stealer(1985)
The universe is growing dark and on Earth it is eternal winter all because a selfish princess is trying to keep the diamond like planet Spectra to herself. Rainbow Brite, a girl in charge of changing the seasons and keeping the universe colorful, steps up to stop the princess. All of her friends help, including a brash, overconfident new aquaintance called Krys. If Rainbow does not free Spectra (and if she and Krys don't stop arguing) everything will turn gray and die.
This TV spot was originally posted to YouTube by seanmc31076.