First Tough Opponent To Beat
Unfortunately my brother gave away our NES years ago, so while I still have the game I don't have a way to play it. So I recentely rediscovered this through the miracle of ROMs.
It's much more difficult playing with a keyboard than controller, but having said that I got used to it pretty easily. I pretty much breezed through it till I got to Soda Popinski then started struggling.
I think the toughest opponents to beat are him, Super Macho Man, Mr. Sandman, and Mike Tyson. It's pretty simple before that, if your a quick learner.
When does it start getting hard for you in the game?
Try not to take life too seriously, no one gets out alive.