 
When you highlight the portrait of the following characters and hold START, you'll see their other portrait in the bottom left or right corner change. Press X, Y, A, or B (while holding start) to select a different version of that character.
The following are available:
Kyo, Terry, Andy, Joe, Ryo, Robert, Yuri, Mai, Yashiro, Shermie, Chris, Billy, & Rugal.
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.
Successfully complete survival mode once. Then, highlight the "Survival Mode" option, hold Start and press A to fight individual characters instead of team battles.
Pause the game and press X + Y simultaneously. The "Pause" message will then disappear.
To play as Orochi team, go to the character selection screen and press START on Chris or Yashiro or Shermie.
To play as Rugal B, complete the game once and go to character select screen press START at Rugal.
After you finish playing, go to NEOGEO POCKET then to DOWNLOAD. Choose POINTPLUS and YES. 
After you reach a certain number of points you will have access to secret 'KOF99 Millenium' images in the UPLOAD menu of the NEOGEO POCKET option.
To get an special ending( or a team picture) beat the game with these teams 
Hero Team: Kyo, Terry, Ryo 
Flame Team: Kyo, Saishu, Chris 
Dream Team 99: Kyo, Iori,Chizuru 
Sidekick Team: Benimaru, Andy, Robert 
Head Band Team: Goro, Joe, Yuri 
Rugal Team: Rugal, Vice, Mature 
Family Tree Team: Ryo. Yuri, Takuma 
Female Team 99: Athena, Mai, Yuri 
Dangerous Team 97: Chin Chang choi 
Sports Team: Ralf, Mary, Lucky 
Heidern Team: Heidern, Ralf, Leona 
Head Band Team 94: Terry, Clark, Lucky 
Orochi Males Team: Yamazaki, Chris, Yashiro 
Orochi Female Team: Vice, Mature, Shermie 
Shingo Team: Shingo, Kyo, Saishu 
Father Team: Kim, Saishu, Takuma 
Rapid Button Team: Joe, Chang, Billy 
Heavy Hitters Team: Brian, Ralf, Chang 
The Crazy Team: Robert, Choi, Sie 
Birthday Party Team: Shingo, Mature 
KOF 2000 Team: Kyo, Iori, Shingo
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.
- More Cheats, Achievements