Secret Codes:
Press Turbo, Shoot, and Pass on the Matchup screen screen to change the icons. The numbers below are the number of times the buttons need to be pressed. After pressing the buttons, you must then press the D-pad (or Analog Stick) in the indicated direction. You'll see the name of the code and hear a sound to confirm entry.

T-S-P-D        Effect
2-0-1-Up       No Hotspots
1-1-1-Down     Tournament Mode
0-0-1-Down     Show Shot Percentage
1-0-0-Down     Show Hotspots
2-0-0-Right    Big Head
2-3-2-Right    ABA Ball
4-0-0-Right    Team Uniform
4-1-0-Right    Home Uniform
4-2-0-Right    Away Uniform
4-3-0-Right    Alternate Uniform
4-0-1-Right    Midway Uniform
4-4-4-Up       No Tip Off
5-5-5-Left     No Goaltending
3-4-5-Left     Tiny Players

Note: These codes only work in the outdoor courts
1-2-1-Left     Snow
1-3-1-Left     Blizzard
1-4-1-Left     Rain
1-2-3-Up       Fog
1-2-3-Left     Night Fog
1-2-3-Down     Thick Fog
1-2-3-Right    Swamp Fog   

Change courts:
Hold the following at the Choose Team screen after choosing your players:

Turbo + Up            Home Team Court
Turbo + Down          Away Team Court

Turbo + Left          Street Court
Turbo + Right         Island Court
Shoot + Pass + Up     Midway Court

Shoot + Pass + Down   NBC Court 

Secret Characters:
Enter the following initials and PIN numbers to play as hidden characters:

Random Players
KERRI 0220      Kerri Hoskins
LIA 0712        Lia Montelongo
RETRO 1970      Retro Rob
PINTO 1966      Pinto
HORSE 1966      White Horse
SMALLS 0856     Small Alien
BIGGY  0958     Big Alien
NIKKO  6666     Devil Dog
GRANDPA 2001    Old Man
CRISPY 2084     Clown
JACKO 1031      Pumpkin
THEWIZ 1136     Wizard
THEREF 7777     Referee

Mascots
HAWK 0322       Atlanta Hawks 
HORNET 1105     Charlotte Hornets  
BENNY 0503      Chicago Bulls  
ROCKY 0201      Denver Nuggets  
TURBO 1111      Houston Rockets
BOOMER 0604     Indiana Pacers
CRUNCH 0503     Minnesota Timberwolves  
SLY 6765        New Jersey Nets 
GORILA 0314     Phoenix Suns
SASQUA 7785     Seattle Sonics 
RAPTOR 1020     Toronto Raptors   
BEAR 1228       Utah Jazz  

Thanks to Revolution readers Rob, Antoine Jackson and MoneyB!