Naruto Shippuuden: Narutimate Accel 2 (Import) Cheats & Tips

To unlock the secondary form of all the characters, just beat the story mode. Then, in VS mode, push R1 to see the secondary form and select for it. This doesn't work on all the characters, only on the ones that have a secondary form in the anime (ie: Neji doesn't have one, but Choji does (his super pill form))

Naturally, this only works on characters that you've already unlocked (which should be all if you beat story mode)

Itachi Beat Itachi in Master (Story) Mode
Sasori Hiruko Beat Sasori in Master (Story) Mode
Chiyo Meet her Master (Story) Mode
Chiyo with Puppets Beat Sasori True Form in Master (Story) Mode with her
Orochimaru Beat Orochimaru in Master (Story) Mode
Kabuto Beat Kabuto in Master (Story) Mode
Sasuke Beat Sasuke in Master (Story) Mode
Kisame Beat Kisame in Master (Story) Mode
Yamato Beat Sai in Master (Story) Mode
Sai Beat Sai in Master (Story) Mode
Sasori True Form Beat Sasori True Form in Master (Story) Mode
Deidara Beat Deidara in Master (Story) Mode

if you want to get him you need to get all characters exept yondaime (4th) and finished all the social, jutsu, special quests and then go to orochimaru hideout and at the first place in the first room you find him fight and win and you get him