Knockback Bros. is a Bros. Attack used by Mario and Luigi during the events of Mario & Luigi: Superstar Saga. The move costs 5 BP on Modes 1 and 2, and 3 BP on Mode 3. Luigi learns this move. Luigi smacks Mario with his hammer, making him a ball, and hits him like a golf ball. The buttons pressed are B to whack Mario, B again to send him shooting toward an enemy, and A to do damage to the enemy.
After successfully executing the attack forty-three times, Mario and Luigi learn the Advanced version. In the Advanced version, mre controls are added. The controls for the standard version are the same, but to execute the Advanced version, A must be pressed immedately after the first B press. Then the controls are B to hit Mario, A to do damage, B to hit Mario, A to do damage, etc.