To play as the hidden teams, press Left, Up, B, Up, Down, Up, Right, C
at the title screen when the words "Press Start" are flashing. You
should hear a quick "clink" when you enter the code. Then, at the
"Team Selection" screen for any mode, scroll down until you reach the
fraternity and other hidden teams.
Pick any of the game modes and select a team. At the Today's Match-Up
screen, rotate the directional pad clockwise for five seconds and
press any button. When the game starts, your character will be a
whirlwind that no player can touch.
Pick any game mode and select a team. At the Today's Match-Up
screen, repeatedly press Up and Down for about five seconds, then
press any button. When the game starts, you can make half-court dunks!