AFC or NFC preseason teams:
Press Y, B, Y, B, Y, B at the copyright screen, then select the "Preseason" option.

Iguana and Acclaim teams:
Press Down, Y, Down, Down, Y, Down, at the copyright screen.

Weak team:
Press Start, Y, Down, Y, Start(2) at the copyright screen.

Strong team:
Press B, Y, Down, Start(2) at the copyright screen.

Invisible opponent:
Press Start(2), B, Start(2), B at the copyright screen.

Slippery field:
Press Y(8) at the copyright screen.

Black field:
Press Start, Y, Down, Start, Y, Down at the copyright screen.

Bouncing players:
Press Down, Down, Start, Down, Down, Start at the copyright screen.

Tackles after play ends:
Press B, Y, Start(4) at the copyright screen.

More fumbles:
Press A, Y, B, A, Y, B at the copyright screen.

No fumbles:
Press B, Y, B, Y, B, Y at the copyright screen.

Up and over dives:
Press A, Y, Start, Start, Y, B at the copyright screen.

Unlimited turbo runs:
Press B, Y, A(2), Y, Start at the copyright screen.

Enable all codes:
Press Down, Start, A, Y, B, Down at the at the copyright screen.

Glitch: Stop time in mid-play:
Call your selected play and snap the ball. After the play has begun, pause game play and call a time out. The game clock will stop, but the play will continue. On the next play call, the game clock will display the time at which the time out was called, allowing the play to be ran without time running off the clock. This is especially useful when your team is trailing with only a few seconds left in the game.