Unlock Characters
Deidara - Complete sidequest 2 - Instead of going South to find Sai, go East, then North-West to find Shino. He will give you sidequest 2.
Four Tail Kyuubi Naruto - ??? - It is unlockable, but how to unlock him remains a secret.
Hoshigaki Kisame - Complete sidequest 1 - see Uchiha Itachi.
Kabuto - Win 15 battles in Survival Mode.
Legendary Sannin - Win 15 battles in Survival Mode.
Non - Shippuden Characters - Win 15 battles in Survival Mode in difficult.
One Tail Kyuubi Naruto - Complete story mode in difficult.
True Form Sasori - Complete sidequest 2 - see Deidara.
Uchiha Itachi - Complete Sidequest 1 - Instead of going South in story mode to find Sai, go East to do the sidequest.
Unlock Exploration Mode
Beat the Story mode once.