Killer Instinct Gold cheats and cheat codes for Nintendo 64

Press the following button combinations during the story 
introduction, when a character profile appears:

Watch the ending credits
Hit Z, L, A, Z, A, R. 

Unlock all options:
Hit Z, B, A, L, A, Z. 

Unlock Gargos as playable character:
Hit Z, A, R, Z, A, B, then go to the character selection screen, 
to choose him.

Change costume colors: 
Hit Z, B, A, Z, A, L. 
You can select new costumes by pressing Up or Down buttons 
at the character select screen

Select characters randomly:
Hold Up and hit Start, while selecting a character.

Watch the high scores:
Hit Z at the main menu.

Music and stage selection:
While selecting a character in 2-player mode, enter the follow 
button combinations. Note: 1st player will choose the level and 
the 2nd player will choose the back ground music.

Level or Background Music: Code
Bridge: Down + QK
Dojo: Down + QK
Dungeon: Down + MP
Helipad: Up + FK
Jungle: Up + MP
Museum: Up + MK
Sky Stage: Down + Z
Space Ship: Up + FP
Spinal Ship: Down + MK
Stonehenge: Up + QK
Street: Down + FP
Wolf Castle: Up + QP