i don't know if anyone has mentioned this, but i found a bug: in the level with the pipe at a 45 degree angle (the middle one in the selection screen) if you fall down below the pipe and then do a coin jump (up+b) into the underside of the pipe, you will stick there- you aren't frozen though, you jiggle up and down a little. eventually the computer will move the screen away which causes you to fall. i can't provide video of this but can someone confirm it.
edit: i'm playing demo 2 downloaded from his website.
edit2: the game has frozen for me once when pressing select to end the battle, but it has worked all other times.
edit3: i stayed stuck there for about 3 minutes until the battle ended. the computer was standing above me and punching/down+a-ing/down+b-ing. the battle ended with the timer without any problems.