Code          Result  
ALL_BOBO      All Bobo teams   
ROCKETMAN     Ball carrier has speed bursts   
LINE_BUSTER   Better defense line   
STICKEM       Better receivers   
SUPER_FOOT    Better kickers and punters   
TINY          Big players  
FASHION_SHOW  Cheerleaders pictures after game   
SMARTER_CPU   CPU team is more difficult   
JACKHAMMER    Crunch time with more hits   
BOOSTER       Fast Players   
TWO_D         Flat players   
POP_WARNER    Floating players  
GRUDGE_MATCH  GameDay stadium   
HAM INJURY    Hamstring injury when player tries to run  
MR_GLASS      Press Turbo for injured hamstring  
ENDURANCE     High endurance   
BIG_PIG       Large football   
GIANTS        Large players   
PENCILS       Tall and skinny players   
MUNCHKINS     Small players   
FLAT_LAND     Flat players   
989_SPORTS    Players named after 989 Sports programmers  
EURO_LEAGUE   Players named after European league stars  
BASKETBALL    Players named after NBA stars   
RED_ZONE      Players named after Redzone programmers  
OVAL_OFFICE   Players named after U.S. Presidents   
FATIGUE       Reduce fatigue   
EVEN_STEVEN   Evenly matched teams   
UNBEATABLE    Unbeatable team   
CREDITS       View credits   
5280_CLUB     Mile High Stadium   
MR_FURIOUS    Maximize game and clock speed in random season

Hints

Unlock Special Teams:
If you go to options and click on the super bowl field and make the temperature 0 degrees you will unlock special teams. like greats or select a year your team won the super bowl. It goes all the way to the 19 century and up to 2001.

Thanks to Revolution readers QB and joseph bourne!