Knucklemaster has only two attacks, smashing the floor with its "body" and becoming a punch to pummel the player with. His first attack is avoided simply by running, however its size makes it tough to avoid if the player runs straight, so it is always recommended to avoid this attack by running towards either side of the boss. Its second attack is avoided simply by merging into a wall while letting the Knucklemaster slam itself into the wall, stunning him. This tactic is needed to later inflict damage on the boss. As the battle progresses Knucklemaster becomes faster when it smashes the floor, and also begins using this attack more times in succession. His pummel attack also becomes faster.
While the mechanic of the boss itself is simple the true difficulty is in the battleground, which is filled with cracks and as the battle progresses the more likely it is for the Knucklemaster to create several holes which not only hamper the player's ability to avoid his attacks, but also may even push the player itself into the holes when attacking which further increases the damage output. All in all the battle must just be handled with care while being mindful of the surroundings, then in a matter of time the Knucklemaster will fall.