Teenage Mutant Ninja Turtles 4: Turtles In Time

Level select:
Highlight the "Option" selection at the title screen, then quickly press Up(2), Down(2), Left, Right, Left, Right, L, R on controller two.

Ten lives:
Highlight the "Option" selection on the title screen. Quickly press Up(2), Down(2), Left, Right, Left, Right, B, A on controller two, then Start on controller one. The "Rest" option on the options screen may now be set to ten.

One player extra continues:
Press Start on controller two just before losing with no continues remaining. Game play may be continued as player two with the continue total reset to full.

Special attack:
Press B + Y to use a special attack. Note: You will lose health by doing this and it is not very powerful.
Information in this section was contributed by tinatanner.

Alternate music:
Enter sound test mode from the option screen. Set the sound test to the "Staff" selection, press B to play the song, then press Y.

Hint: Extra points:
Throw your opponents at the screen for more points and lives.
Information in this section was contributed by Pika312.

Hint: Defeating Super Shredder:
Use the following strategy to defeat Super Shredder under the hard difficulty setting: If you are using Raphael, then Shredder is easy. Keep moving to avoid his attacks, and move in and hit him when you see him do the blue ice attack. However, for the other three turtles, Super Shredder will be too fast if you use the entire stage to fight him. Instead, move to either side of the screen and stay there. This way, you keep the distance between you and Shredder manageable. Move only up and down to avoid his red and green flame attacks, and move in to attack only when he flashes blue. Try to stay very close to him and be ready to strike. Be patient and do not go after him if he teleports very far away from you, even if he is flashing blue, as you will not reach him in time. For him to come to you and he will. Do not attempt to attack him when he is about to do the red flame or green energy ball. He will probably still get you a few times if you move too slow.
Information in this section was contributed by Abdul Jamal Okmed.

Hint: Defeating blocking enemies:
Whenever you face an enemy that blocks, jump with B, then kick with Y very soon after the jump. If done correctly, you should diagonally kick and break the blocker's guard.
Information in this section was contributed by tinatanner.

Hint: Avoiding throwing stars:
When someone throws a star at you, press Hit and the star will backfire.
Information in this section was contributed by tinatanner.