Everything was sent in by Johnny

At the legal screen (the screen with all the writing that you see when
you start the game) press Y until you hear a clicking sound. This is
for the ground to be slippery no matter what the conditions may be.

More codes to do at the legal screen.

B, Y, Down, Start, Start-For a strong team.

Y, B, Y, B, Y, B-For NFC and AFC teams in the preseason.

A, Y, B, A, Y, B-The first two hits create a fumble.

Y, Y, Y, Y, Y, Y, Y, Y-Slippery Field.

B, Y, B, Y, B, Y-No fumbles.

B, Y, Start, Start, Start, Start-Hit players down after play is over
as long as someone is on the ground.

A, Y, Start, Start, Y, B-All dives are up and over.

B, Y, A, A, Y, Start-Unlimited speed bursts.

Start, Y, Down, Y, Start, Start-The team you choose is the worst.

Down, Y, Down, Down, Y, Down-For Iguana and Acclaim teams.

Start, Y, Down, Start, Y, Down-Pitch black field.

Down, Down, Start, Down, Down, Start-Springs randomly come out sending
players into the air.

Start, Start, B, Start, Start, B-Your opponent is invisible.

Down, Start, A, Y, B, Down-all the codes at once!