Enter the options menu and select "Gameplay." Hold D-Pad Left + Left + Analog-stick Right and press start. The "Codes" selection will now be unlocked at the options menu.
Bonus teams:
Enter the code MEGASTARS to unlock the Sega Sports, Visual Concepts, and Team 2K2.
Easily Get to Playoffs:
You want to beat the other team by a landslide and make it to the playoffs easly. After you setup everything in the season, go 2 NBA Rules and turn everything off. Then go and start playen yor first game. When the other team has the ball, then intentionlly pull a foul on them. It wont affect you cuz you have everything off. Keep doing this when they have the ball. I Got 2 112 - 2 with my team being the 76ers.