First one jump away from sub-zero. Use any character. While he's just standing there wondering what he should order form burger king, jump toward him. He will do the "Ice Shower" move. This gives you an opportunity to to jump kick/punch them or use an special attack. Be warned, however: The ice move may reach you and you will be frozen.
Works best with Classic Sub-Zero or the real Sub-Zero. Back up so you are cornered. When the enemy is close, freeze them then jump over them and push them to the corner. Back away one step then rapidly push Low Punch. normally they will stumble back so you can't hit them, but now that they are cornered, there is no escape. With the enemy having full health, the combo meter should say 19 hits 99% damage. With no fatality or anything, full heath, the meter says 31 hits 99% damage. Awesome right?
Use Shang Tsung. Ner the end of the second (or third) round while the other guy has almost no health, transform into Scorpion or Classic Sub-Zero, then beat the guy. Preform your censored fatality. The screen will go black, as normal However the words Shang Tsung Wins Fatality! will appear and so will Shang Tsung and his win pose while everything is in a black backround.
To play as Human Smoke, select ROBO Smoke. Right before the battle begins, Press and hold, BLOCK+RUN+HighPunch+HighKick+BACK. You should see smoke flaming into Human Smoke.
Enter the following kombat codes after you are defeated in Ultimate Mortal Kombat 3 to unlock the corresponding characters
Classic Sub-Zero 81835