Naruto Ultimate Ninja Message Board  

For naruto ultimate ninja 2, go to naruto's house. Then put in password. Select the element lightning. Then

Snake
Rat
Dragon.

Then you will unlock all characters.

And if you don't wanna cheat here's how you unlock all characters without cheats

Story Mode Character Unlocking
Haku: Beat Haku with Uchiha Sasuke in story 4.
Hatake Kakashi - ANBU: Beat story 4.
Hoshigake Kisame: Beat story 4.
Jiraiya: Beat Jiraiya with Uzumaki Naruto in story 1.
Momochi Zabuza: Beat Momochi Zabuza with Jiraiya in story 4.
Orochimaru :Beat story 4.
Orochimaru - Sealed: Beat story 2.
Sandaime Hokage: Beat Orochimaru with Sandaime Hokage in story 1.
Shizune: Beat Shizune with Tsunade in story 2.
Tsunade: Beat story 2.
Uchiha Itachi: Beat story 4.
Uzumaki Naruto - Kyuubi: Beat story 4.
Yakushi Kabuto: Beat story 3.

The Last 2 Hidden Characters
After finishing the entire story mode (4 arcs), these can be done at any time.

Hyuuga Hinata - Successor: Speak with Hyuuga Hiashi outside the arena. Then at the rooftop. Then speak with Hinata at the training grounds. Head to the arena and beat Neji.
Uzumaki Naruto - Maito Suit: Speak with Maito Gai at the marketplace. Head to the next city and buy a Maito suit (100.000 mon). Head to the next screen and fight Gai.