Mega Man Powered Up/Guts Man

Boss: Guts Man
Stun weapons: Mega Buster (charged), Time Slow, Proto Strike

Mega Man: Guts Man will pick up a rock, jump a couple of times and throw it at you. When he lands, he'll make an earthquake, which will stun you. Jump as soon as he's about to hit the ground to avoid being stunned. Guts Man's special attack causes him to dig into the ground and then jump with a rock in his hands. When he dug in, run to the wall, wait a bit and jump out of the way. If you jump too late, you'll get hurt by Guts Man's rock. On Hard, Guts Man will also throw a rock at you and then repeat this attack 2 more times.

Guts Man's weakness is Time Slow, but it can be used only twice by Mega Man. If you play as Time Man, simply use Time Slow until he dies, otherwise use Mega Buster or charge shots (when playing as Mega Man C).

Cut Man: Cut Man is weak to Guts Man's Super Arm, so rocks will cost you a lot of health. Try to attack Guts Man when he's not holding the rock. You can also use wall-jumps to avoid rocks.