okay did now that we've seen everything let's see if Mask can take Kid muscle.
Kid Muscle gets stomped.
Speed equalised? No problem, Mask still stomps. His hits when he got serious sent his opponent flying a mile away. His durability would also make Kid's attacks look like nothing, not to mention he can fire blasts that can one-shot Bleach captains.
To give some perspective: Kevin Mask was using a demolition ball to hit himself in order to prepare for Kid's muscle millenium (I think that's the name). Any of the sternritter would laugh themselves silly at a demolition ball.