Ash and Shiva both appear on the select screen (with portraits) in addition to all of the other characters if you do the Roo code (On the title screen hold Up+B on Controller 1 and press Start). Characters are then fully playable.
Bare Knuckle III (J) [!].bin
CRC32: 5D09236F
MD5: F1CB9E887BF4BC512D9535C89E420DF7
SHA-1: B9B2B4A98A9D8F4C49AA1E5395E2279339517FDB