Not sure if this has been mentioned yet, but Magma Bazooka at point blank does 2 bars of damage, even on Magma Man himself. If you miss a bullet, you can always pause to erase it. This is a lot faster than Mega Buster when you're fighting Robot Masters that easily diminish your weapon energy (more specifically, Magma Man and Plug Man). Also, it's probably better to start off the Magma Man match with T. Blows instead of shooting first in case you get a
by luck (or skill). It's happened to me during some time trials even while pausing between each shot.
And from watching the video, the 1st Wily form took you quite a bit of time. It's a lot easier to hit him consistently by shooting while standing or at the peak of a jump. What I usually do to speed up the process is after the egg rebounds the 1st time, if it rebounds off his jaw, I just jump shoot 2 shots so that at the moment it rebounds, the buster hits it right back at the mouth.
Hope that helps, and good luck. I was considering attempting an All Clear run, but I'm seriously burned out from clearing all the challenges and making "perfect" files...plus, no time on my hands.