NBA 2K3 cheats and cheat codes for Gamecube

Go to the options menu after choose "Gameplay".
Hold D-pad Left + Left Analog-stick Right and press Start.
This will unlock the "Codes" selection in the options menu.
After enter the following case-sensitive codes:

3 bonus teams: Enter MEGASTARS
Trash in the streets: Enter SPRINGER
Black and white Graphics: Enter DUOTONE

Easy lay-up
While doing a dunk, push Square in the air to do an easy lay-up.