King Of Fighters Dream Match '99 Codes -

Fight as Boss Rugal:
Highlight Rugal at the character selection screen, then hold Start and press X.

Fight as Orochi Team:
Highlight Chris at the character selection screen, then press Start.

Full pause screen:
Pause game play and press X + Y.

Alternate costumes:
Highlight one of the following fighters at the character selection screen, then hold Start and press X: Andy, Billy, Chris, Joe, Kyo, Mai, Robert, Ryo, Shermie, Terry, Yashiro, Yuri.

Alternate costume colors:
Select a fighter at the character select screen with one of the following actions.

Normal color: A
Second color: A + X
Third color: A + Y
Fourth color: A + X + Y

Alternate survival mode:
Successfully complete survival mode once. Then, highlight the "Survival Mode" option, hold Start and press A to fight individual characters instead of team battles.

Teammate assistance:
Hold B when selecting the fighter order before a match. Note if any of the characters are neutral or friendly. If your fighter is stunned during the match, hold X + Y + A to have your teammates enter the fight.