Choose a few teams of four people each at random from the audience. Provide each team with art supplies such as streamers, posterboard, markers and glitter. Give them 10 minutes to come up with a team spirit-themed work of art. Ask the audience for help in choosing the winner. The team that receives the loudest cheers from the stands wins.
Choose five students from each grade if your school has four grades and 10 students if you only have two grades. Ask each student to take their shoes off. Place their shoes in a pile in the middle of the gym floor. Put students from different grades on opposite sites of the room. Have them run to the middle of the gym, find their shoes, and get back to where they started. The grade that finishes first wins the challenge.
Borrow a bunch of the cheerleaders' pom-poms. Put as many as you can fit into a large, clear container. Have each student write their guess down for the number of pom-poms in the container. Put all of the winning ballots into a box and pull one lucky winner. Give this student a pair of free tickets to the game.
Have your school's mascot and someone dressed as the mascot from the school that you're playing compete against each other in a few funny competitions. It will need to be pre-planned that your mascot will win every competition and the person dressed as the rival mascot will act so uncoordinated that he has no chance of winning. This is a funny pep rally activity that will encourage a sense of school spirit amongst your students.