Mortal Kombat 2

Random character select:
Hold Up on Liu Kang for player one (or Reptile for player two) and press Start.

Alternate introduction sequence:
Hold L + R before the Acclaim logo is displayed and keep the buttons held until it disappears.

Four man endurance match (two-player):
Hold L + R, then press Start at the start/options screen.

Miscellaneous codes:
Quickly enter the following controller actions at the "Select Your Fighter" screen. A sound will confirm correct code entry. More than code can be enabled as long as only one is a character code.

Thirty kredits
Press Left, Up, Right, Down, Left + Select.

Triple time for fatality moves
Press Up(2), Left, Up, Down + Select.

Extra damage on attacks
Press Down, Up, Right, Up, Left + Select.

Fight against Smoke
Press Up, Left, Up(2), Right + Select.

Fight against Jade
Press Up, Down(2), Left, Right + Select.

Fight against Kintaro
Press Up, Down(2), Right, Right + Select.

Fight against Shao Kahn
Press Right, Up(2), Right, Left + Select.

Fight against Noob Saibot
Press Left, Up, Down(2), Right
+ Select.

Pong mini-game:
Win 250 consecutive matches in two player mode.

No throws:
Select a two player game. Hold Down + HP on controllers one and two after character selection. Release the buttons after the match starts.

Mystery sound:
Press Down after executing the Dead Pool fatality.