When bands battle in the show, it's called a Sound Clash. Sound Clashes normally take place in a dimensional rift, so as not to damage the area around the battling bands. However occasionally Freefonix (Band) and Mantyz have been known to Sound Clash out of the rift, for example in the episode Mr Start’s Opus when they battled in Aw'right Jack's restaurant and broke his karaoke machine.
A Sound Clash is usually declared by a member of one of the participating bands before it starts. As soon as it is declared, the rift surrounds the bands so they can battle.
Different instruments do different things in the clashes. For example, Lady Lux's bass guitar creates cage like energy to trap enemies. Mo's Soundshaper creates a forcefield to protect the band. Even though the characters get blasted and hit by the energy, it doesn't seem to harm them or do any lasting damage. This could be due to the dimensional rift the clashes take place in.