Cheat mode:
Press Turbo, Jump, and Pass to change the icons below the helmets on the versus screen. The numbers in the following list indicate the number of times each key/button is pressed. After the icons have been changed, press the joystick/gamepad in the indicated direction to enable the code. The name of the code and a sound will confirm correct code entry. Example, to enter 1-2-3 Left, press Turbo, Jump two times, Pass three times, Left.

Result - Code:

Big head - 200R
Team big head - 203R
Team big players - 141R
Team tiny players - 310R
Big football - 050R
Hide receiver name - 102R
Rainy weather - 555R
Night game - 222R
Headless team - 123R
Throw unlimited distances - 223R
No CPU assistance1 - 012D
No random fumbles - 423D
Smart CPU opponent - 314D
Shows field goal percentage - 001D
Tournament mode in two player game - 111D
Snowy weather - 525D
Unidentified call carrier - 522D
Power-up offense - 312U
Power-up defense - 421U
Power-up teammates - 233U
Super blitz - 045U
Unlimited turbo - 514U
No punting - 151U
No interceptions - 344U
No first downs - 210U
Huge head - 040U
Late hits - 010U
Invisible - 433U
Clear tournament mode1 - 111U
Super blitz1 - 444U
Turn off stadium - 500L
Fast passes - 250L
Fast turbo running - 032L
Power-up blocker - 312L
Allow stepping out of bounds - 211L
Super field goal - 123L
No heads - 321L
Clear weather - 212L
Invisible receiver highlight - 333L