Alternate Costumes
On the character select screen, highlight a character and press Y.
Unlock 9 tailed fox Naruto
To unlock 9 tailed fox naruto beat 1 player mode with every characher 2 times after you get Rock Lee.
Unlock Extra Characters
Rock Lee - Beat Zaibuzan in story mode without using continues, and then beat Rock Lee when he appears.
Kyuubi Naruto - Unlock Rock Lee, and then beat the game with all characters. Now highlight Nartuto on the character select screen and press X or Z.
Sharingen Kakashi - Beat the game with Kyuubi Naruto, and then beat the game with Kakashi. Now highlight Kakashi on the character select screen and press X or Z.
Unlock Hinata
Clear story mode using Sakura. Find this fighter by highlighting Rock Lee and pressing X.
Unlock Sound Test
Beat the game with every default character.