In Dead or Alive: Dimensions for the Nintendo 3DS, there are several boss characters that can be unlocked.
Here is the list of unlockable boss characters, and what you need to do to unlock them. Before you can unlock them, you must first complete Chronicle Mode.
Alpha-152 – Complete Mission 19 in Tag Challenge mode
Genra – Complete Mission 18 in Tag Challenge mode
Kasumi Alpha – Complete Mission 16 in Tag Challenge mode
Raidou – Complete Mission 20 in Tag Challenge mode
Shiden – Complete Mission 20 in Tag Challenge mode
Tengu – Complete Mission 17 in Tag Challenge mode
Note: In order to select Shiden, you need to hold L + X and press A on the Random option on the character selection screen
