The Freshwater High Marching Band is a group of band members led by Lonnie.
When Milo made a band after he got rejected by Lonnie the band leader, Lonnie and the marching band came to Milo, Oscar, and Bea, and got rid of their instruments. After Milo left the music room, every student who got rejected by Lonnie in band tryout revealed that Lonnie doesn't let anyone play their instruments after they get rid of them. This causes Milo to still play his kazoo, which causes Lonnie and the band to destroy Milo's kazoo. At band practice, one of the band members named Wilmur told Lonnie that his sousaphone was sticky. Some other band members noticed that their instruments were covered with honey, which was done by Milo for revenge. Lonnie goes up to Milo and he challenges Milo, Oscar, and Bea in a "Battle of the Bands against Lonnie and the marching band. If Milo wins, Lonnie will allow everyone to play music. If Lonnie and the marching band wins, they will not let anyone play their instruments forever. At the battle, several other students helped Milo defeat Lonnie. Milo became victorious, so Lonnie had to allow everyone to play their instruments again ("Banned Band").