Here are some cheats and tips for the game King of Fighters Dream Match ’99.
Fight as Boss Rugal:
Highlight Rugal at the character selection screen, then hold Start and
press X.
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.