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. 

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.