P.P.S. Let me just get it out of the way. The Konami code is UP, UP, DOWN, DOWN, LEFT, RIGHT, LEFT, RIGHT, B, A then select, start (for 2p) or start (for 1p). This works for games such as Contra, Lifeforce, Gradius, and more. Enjoy!
Invincibility: Press A(2), Up, B(2), Down, A, B, Start at the credits screen.
View end game sequence: Press A(2), Up, B(2), Down, A, B(2), Start at when the phrase "Press Start" appears.
Level select: Press Left, Up, Right, Down, Up, Right, Left, Down and one of the following buttons at the credits screen.
Level Button
2- Up
3- Left
4- Down
5- Right
6- Select
7- B
Level Select: After the coconut bonks Higgins on the head and the title appears, push right, left, right, left, A, B, A, B. You can now choose your level.
Stage select: Push up, down, left, right, B, B, B, B, start at the title screen.
Invincibility: Push up, up, up, up, left, right, up, start at the title screen.
Super weapons: Select Team Edit,then choose Team A or B, then enter "Terminator 2" as your name. Now, Team A will have Laser Guns or Team B will have Laser Swords.
Six lives: Hold Down + B + A and press Start at the title screen or continue screen. An explosion will confirm correct code entry. Alternatively, hold Down and press A, B, Start at the title screen or continue screen.
Continue game play: Allow the continue timer to expire after one of the players loses all lives. Press Start on the next map screen to continue game play.
Battletoads and Double Dragon-
Begin with 5 lives: On the character select screen press and hold A,B and Up then START
30 lives (you know you couldn't live without it)- Use the Konami Code, UP, UP, DOWN, DOWN, LEFT, RIGHT, LEFT, RIGHT, A, B, then START (1p) or SELECT, START (2p).
Location select: Hold A + B on controller one and press A on controller two during game play to jump to a new location. Keep pressing A to visit up to ten different game locations.
Move past obstacles: Stand next to the person blocking that path, then hold A and walk into them two times to eliminate the messages that will appear. Then, press the D-pad in the direction opposite to that being blocked. Repeat this to eventually push past the obstacle.
Pause game play: Press B on controller two to pause the game.
Full Weapons- Use the Konami Code (see top).
Cheats-
Begin game with 30 lives- When the title screen appears, hit A, B, right, left, right, left, down, down, up, up then start.
16 of everything: On the title screen press and hold on control 2 Up+Right, A and B. At the same time hold on control 1 Down+left and Select. With all that held press Start
on control 1. If you did this right you should hear a tone.
Now select Roas (boy), go outside, and try to buy a crystal from the tree
shop. Return home, select Roas again, go outside, and waste away all of your
magic power.
Return to the house, and place the finger of the pointer on the eyes of the
picture on the wall.
Press and hold on control 2 Left and B, and on control 1 Right. Don't allow
that pointer to move! While holding all that down press A sixteen times on
control 1. You now have 16 of everything! (except crowns and dragonslayer
sword).
Fast save: Press Start to display the options menu, then press Up + A on controller two. The game save menu will appear (this REALLY helps when you are using the 'take no damage' Game Genie Code)
No broken door charge: Press A + B on controller two after the old man asks for payment for a broken door.
Unlock door in first dungeon: During the First Quest, enter the first Dungeon for the first time, then turn around and immediately exit. Turn back around and re-enter the first Dungeon. The locked door at the top of the screen will be open.
Cheats-
Begin with 30 lives- On the title screen hit UP, UP, DOWN, DOWN, LEFT, RIGHT, LEFT, RIGHT, B, A, START
Super jump: Hold Right on controller two and press A on controller one.
Quit game play: Press Start to pause game play. Hold Up + A on controller two to display the current password.
Cheats-
To begin with 20 lives- On the title screen hit A, B, A, B, UP, UP, DOWN, LEFT, START.
Passwords/Cheats-
Super powerful shots- Enter the password CKWJT4 (press up on the title screen to get the password menu).
To continue where you died after your game ends hold Up, A and B and press Start.
Continue game play: Hold A at the game over screen. While keeping that button held, press Start when the title screen appears. Alternatively, hold A and press Start(2) at the title screen.
Teenage Mutant Ninja Turtles 3-
Cheat mode: Press Up Up, Down down, Left, Right, Left, Right, A, B, Start at the title screen. For two players, press Up up, Down down, Left, Right, Left, Right, A, B, Select, Start.
Level select: Press Downx5, Rightx7, B, A, Start at the title screen.
Begin with 10 lives- On the title screen hit UP, RIGHT, RIGHT, DOWN, DOWN, DOWN, LEFT, LEFT, LEFT, LEFT, B, A, Start.
Level 10: Hold A and press Start when selecting a level to begin game play on level 10.
Extra points: Allow the demonstration mode to run. Press Start while the screen is blinking after the CPU forms a Tetris. Begin a game to collect the points from the demonstration game.
Cheats-
More energy: Intentionally die immediately after starting game play. Continue the game to restart with another energy tank. Repeat this process again to start with three tanks.
Quit game: Press Start on controller one, then hold Up + A on controller two.
Easy experience: Save the game after completing the game once. Use this character to complete a castle. Press Start on controller one, then hold Up + A on controller two. Save the game and immediately begin game play with a new character. The new character's experience points will rapidly increase after starting.
Alternatively, complete the first quest, then go to one of the palaces during the second quest. After he has placed the crystal in the statue, his experience points will quickly increase. While this is occurring, press Up + A on controller two. Select the save option and then resume game play with a new character. This new character will also gain experience points quickly.