Meeting certain requirements allows you to face an extra boss after defeating Seth. Like Seth, they are powered up versions of the normal playable character. All number requirements must be met before fighting Seth. All numbers assume the normal 3 round setting.
HOW TO UNLOCK
Never lose a round and get 1 Perfect victory
Never lose a round, get 1 Perfect victory, and defeat Seth with a Super or Ultra combo
Never lose a round, get 1 Perfect victory, get 10 First Attacks, and have 5 Super or Ultra combo finishes
Never lose a round, get 1 Perfect victory, get 10 First Attacks, have 5 Super or Ultra combo finishes, and defeat Seth with a Super or Ultra combo