Use hidden character Hagane:
   Finish the Theater Mode in any difficulty, then you can use Hagane in Tournament Mode.
                              Use Boss character Merkuar:
     Finish the Tournament Mode with any character, then you will get
Merkuar.
                                    Use EX Rickey:
                 Finish the Tournament Mode with Hard difficulty
                                     Use Sieguei:
                  Finish Tournament Mode with Easy difficulty