If you knew every characters moves he was the ultimate character. He could change into ANY other character and had ALL of their moves, including their fatalities.
Actually I used to try to win the match as subzero and freeze them and then morph into another character and do their finishing move. Created a lot of interesting results.
MK3 was good, except for the ridiculous combos which the AI would start spamming relentlessly. Not fun.
All you had to do is block the initial hit which always left them open for a throw.