Hard Knuckle

Hard Knuckle is Hard Man's power. Hard Knuckle may be slow, but it packs a punch. When utilized, there is a 2 second delay before the weapon starts traveling. This also serves the same purpose as the Crash Bomber in that it can break through certain barriers (though these only appear in the first and third sections of Wily's hideout).

It should also be noted that you can slightly guide them up or down once they're moving.

Robot Masters And Bosses Weak Against Hard Knuckle

 * Top Man: Mega Man 3 and Mega Man II
 * Hard Man (2nd Encounter): Mega Man 3
 * Doc Robot (Metal Man, Crash Man and Wood Man): Mega Man 3
 * Yellow Devil: Mega Man 3
 * Copy Robot: Mega Man 3
 * Wily Machine: Mega Man 3
 * Gamma 1: Mega Man 3
 * Quint: Mega Man II
 * Buster Rod. G: Mega Man: The Wily Wars
 * Magmard Serpent: Mega Man: The Wily Wars
 * Wily Machine: Mega Man: The Wily Wars

Robot Master And Bosses Immune To Hard Knuckle

 * Needle Man: Mega Man 3 and Mega Man II
 * Doc Robot (Flash Man): Mega Man 3
 * Gamma 2: Mega Man 3

Trivia

 * The Hard Knuckle is nearly identical to the mega arm in the sense that both weapons fore MegaMan's fist.