Zack and Slater are involved in the annual prank war against Valley, which takes place the same time as the big cheerleading competition between the schools. Screech is the Bayside mascot and has an important part in Bayside's routine. However, after Zack and Slater kidnap Valley's mascot, two students from Valley kidnap Screech. Fortunately, their plan is ruined when the fake mascot ends up winning the competition for Bayside.
Despite Mr. Belding's warning for Zack and Slater to behave themselves, they become locked in a notorious prank war against two Valley High students, Stan and Dan Clegg; this happens on the day of the annual cheerleading competition with the other schools. The prank war is a big deal for the students of Bayside High, as the winner of both the prank war and the cheerleading competition will have bragging rights. Slater and Zack desparately want to keep this title from the Clegg cousins.
During that time, Kelly and Lisa convinces Jessie to join the cheerleading squad since she knows most of the routines. Her feminist side clashes with the other squad when it comes times to create a new routine. Eventually, Jessie helps them create a new routine to help Bayside win the competition.
At Bayside, the prank war has escalated after the Clegg cousins trash Bayside from a previous prank. In spite of getting Mr. Stingwell to agree to end the prank war(though it's likely he won't), Zack and Slater steals the Valley mascot, the bulldog in retaliation. Using the moment to take a picture of Mr. Belding, the cheerleaders, along with Screech(in the tiger mascot costume) and the bulldog. Stan and Dan retaliates further by kidnapping Screech. Mr. Belding finds out that Zack and Slater had continued the prank war and orders them to return the dog at once.
Dan has an ace up his sleeves and instead will pose as the tiger to screw up the routine for Bayside High. After the mascots were returned, Zack and Slater senses something awry. This is later proven true when Screech arrives in the school and revealed the Clegg cousins' plan to humiliate Bayside. Thinking fast Zack and Slater secretly put fleas in the costume and with that Dan's folly helps win the cheerleading competition for Bayside. Zack and Slater uses this to expose the Dan and his cousin, Stan as the perpetrators behind Screech's kidnapping and wanted to ruin Bayside's chances of winning the competition. Mr. Stingwell later shows up to collect the Clegg cousins to face proper punishment. Bayside wins both the competition and prank war bragging rights.
- This is the only time Principal Stingwell takes his job seriously.