Plasma Sword Cheats (Dreamcast)

At the character selection screen, highlight Rain, then press down, down, left, left, up.

At the character selection screen, highlight Byakko, then press up, down, left, left,
right, left, up.

At the character selection screen, highlight Gamof, then hold Start and press A.

Though I'm not sure what triggers her appearance, if Kaede shows up in one of the random
matches (that is, not five, eight or 'nine') and you defeat her, she automatically
appears on the roster of selectable characters from then on. So be sure to save the game!