Some Characters you unlock By Either Winning matches,Getting wi-fi points,or by getting Regional cards

Unlockable	How to Unlock
Haku	Get 10 regional cards
Jiraiya	Play 10 rounds(doesn't matter win or lose)
Nine-Tailed Naruto (OTK)	Get 100 Wi-fi points
Sasuke	Win at least 1 wi-fi match then talk to the guy next to Anko
Sasuke Second-State	Get 30 regional cards
Tsunade	Play 20 rounds(doesn't matter win or lose)