Play as Male Shadow
     At  the Character Selection screen, highlight the ? box and press
Select 5 times, then press any button.

Play as Female Shadow
     At  the Character Selection screen, highlight the ? box and press
Select 7 times, then press any button.

Play as Image Talbain
     At the Character Selection screen, highlight Gallon, hold Select,
then press all three Punch or Kick buttons.

Play as Oboro (Shin Bishamon)
     At  the  Character  Selection  screen,  highlight  Bishamon, hold
Select, then press any button.