She's the love interest of Bobby from A Goofy Movie.
She is Roxanne's best friend as well as the student body president. She is also one of the many characters in the opening song "After Today."
On the last day of term at Spoonerville High before the summer break, Stacey tells the other students at an assembly that she will be hosting an end of school party that features a Powerline concert live on Pay-Per-View. While at her party, she and Roxanne get sprayed with cheese wiz by Bobby and as he drops his cheese, she goes to pick it up and she and Bobby's hands meet and they fall in love.
Just like Roxanne, she is not shown in the direct-to-video sequel, An Extremely Goofy Movie. It can be assumed that she and Bobby broke up and or go to different colleges. Though it's most likely the former as in the film, Bobby is seen flirting with Beret Girl.