She is a cheerleader in part 2 on the bus when she talked to her friends Minxy and Rhonda. Next they started smoking and got in trouble for it by their coach Charlie later she survived when everyone saw the creeper when they were outside the bus and they started running away from the creeper while he was flying up in the sky trying to get them! After Scotty died and the creepers attention wasn't on Chelsea anymore so Chelsea ran back to the bus for safety not expecting the creeper to fly back too the bus. Jonny, a student who stayed on the bus, let her in once he got to having a romantic attraction to her. Later another student, Andy "Bucky" Buck, escaped from the creeper and climbed up the bus and slid down the pole that the creeper pulled him off of. She and Jonny knew the creeper wanted him so they started walking away and the creeper grabbed Bucky but the creeper lost grip and Bucky survived. Later Chelsea, Jonny and Bucky got picked up by Jack Taggart Sr., Jack Taggart, Jr. (Jacky), and Minxy and that was when they saw Dee being captured by the creeper that was when Jack Taggart Sr. shot the creeper to save Dee so Dee survived. He then repeatedly stabbed the Creeper until its time was up and it fell into hibernation once more. 

Jonny, Bucky, and Chelsea

Chelsea, Bucky, and Jonny staring at the creeper out the bus

Jack Jr, Jonny, Chelsea and Bucky

Chelsea at the end of the movie with Jack Jr, Jonny, and Bucky staring at the creepers wounded body