is it actually confirmed that C. Kameo and Head Hunter are unused enemies? I recall that Warrior had the same status until it was recently discovered as a secret mini-boss encountered twice in Bando. It is possible that they are used enemies, but found in unexpected locations or it could be that due to some bug or oversight that they are never encountered. I know for a fact that with cheating devices they can be fought. Chairman and KARI, however, are a lot less likely to have given sprites.