Crash Man - Boss Fight
Crash Man is weak to Air Man's Air shooter. He jumps when you shoot, but the exact angle is slightly random. If there are no Crash Bombs on the screen when he jumps, crash will also shoot at Mega Man.
Refights Patterns
As posted by Aurel in the Mega Man 2 channel - These gifs apply to Normal Mode.
Low Jump pattern
Jump and Shoot once at the peak of your jump, then jump and shoot again before landing on the mine. The second shot should kill a jumping Crash Man and let you teleport out instantly. (Obviously this means no health refill)
High Jump Pattern
Similar to the low jump pattern to start, but this one requires taking a hit to go fast.