If you've ever played the Mega Man X series, you should know how fast X is. His attacks are immensely powerful, and as previously stated, they're ranged. Pushing a Koopa shell towards X won't help due to his protective armour.

Mario would get his ass handed to him in no time at all.

"Stephen Wolfram is the creator of Mathematica and is widely regarded as the most important innovator in scientific and technical computing today." - Stephen Wolfram