Select Mortal Kombat II from the main menu and fight your way up the ladder until you've defeated all kombatants. Shao Khan is the final boss.
Mortal Kombat II is a BITCH. Let's get that out of the way first of all.
The other two games are hard, this will have you crying in a corner. It not only knows your moves but it knows your next THREE moves before you've even thought of them.
Most of the characters will quite happily walk into your sweep in the early matches if you shuffle around for a second while they're down, then sweeping them again while they attempt to get up.
I found that most of the cast were quite happy to walk into Baraka's Blade Shredder too when walking backwards. Baraka is also a great character to use as you can jump back against the wall and punch them in the face and then follow this up with his Blade Swipe move.
Shang Tsung: I found the best way to kill Shang Tsung was to jump around the screen and kick him while he's vulnerable. Jump kick him while he's jumping towards you or sending a fireball your way. Just keep moving constantly over him. Confuse him.
Kintaro: Kitana's Air Wave is great use here if you jump in to Kintaro and input the move as he's blocking, you'll land and lift him straight away. As he's floating, jump towards, land, then uppercut. You'll catch him on the way down. You must have good timing for this but practice makes perfect and it's a surefire way to win.
Shao Khan: I got a double flawless on Shao Khan by doing Baraka's Blade Shredder constantly. He just walked into it every time.