This patch will allow Mario to punch. When you do punch a sliding effect is simulated. So make sure enemies you want to be able to be killed are able to be killed by sliding (you can use Tweaker or whatever to enable that). Also sorry for the poorly drawn GFX, I'm not good at drawing them :(.
Accepted on the grounds that the patch fulfills its rudimentary purpose. With that said, this patch hasn't aged particularly gracefully.
One is able to punch while cape-spinning, throwing a fireball or spin jumping; punching is allowed during the goal walk, as well. Setting the punch speed to a nonzero value feels clunky while in motion, especially in the air, though I do appreciate the option to have punching not affect player momentum. Punching briefly simulates sliding, but due to how sliding works, punching while on a slope will cause the player to assume pose #$01 (due to the setting of $13ED) and keep sliding despite not touching Down on the D-pad. A similar effect is achieved by punching the side of the screen in an autoscroll level.
Tested with Asar 1.71, Lunar Magic 3.04, SA-1 1.32, Snes9x 1.59.2.
Remoderation notes: made asar and SA-1 compliant, optimized the code a bit, fixed a bug regarding the check for Mario's direction and added a couple more customization option. Also added the screenshot.
Note that the GFX file provided only includes a punching GFX for big Mario. Tested with: asar 1.71, SA-1 1.32.