Naruto: Clash of Ninja Cheats
Highlight a fighter and push Y instead of A in the character selection prompt.
In story mode use no continues and beat Zaibuzan. Beat Rock Lee when he becomes visible to unlock him
Unlock Rock Lee, then finish the game in single player mode with every character. Then, highlight Nartuto in the character selection screen and push X or Z
Unlock Kyuubi Naruto, then finish the game in single player mode with him. Now finish the game in single player mode with Kakashi. Highlight Kakashi in the character selection prompt and push X or Z.
Finish the game with all default characters in single player mode to unlock the "Sounds Test" option in the Omake menu.