Bully Battery is a glitch that uses speed from knocking an out of bounds bully repeatedly to allow Mario to gain hyperspeed.
If a bully is out of bounds, Mario runs into the bully repeatedly in order to very slowly cause the bully to gain speed with each hit. After, we can transfer the built speed back to Mario to move at hyperspeed. However, Mario needs to either use water or a squish cancel to escape the knockback state. Otherwise, the built up speed is immediately lost.