The farther you get in the competition, the more liberal the rules become. For instance, in early rounds competitors start on their knees and no leg locks are allowed. However, the more you win and show mastery of basic skills, the more you can use advanced techniques.
Here are the rules for the final rounds:
WAYS TO WIN A MATCH
KNOCKOUT: Fighter is unable to intelligently defend himself after being hit by a strike(s).
TKO: If the ringside physician or referee decides the fighter cannot continue due to a cut or other injury.
SUBMISSION: When a fighter submits by tapping the opponent or the mat “three” times or more from a choke, lock or for any other reason. If a fighter is in no position to tap out, he may verbally submit. If a fighter cannot tap or yell, the referee shall stop the bout from his own personal determination of the fighter's safety.
REFEREE STOPPAGE: When a fighter is taking excessive punishment but cannot or will not submit or quit either due to striking, failing to show a willingness to continue, refusing to submit in the face of grave injury, or any other reason the referee believes is necessary to preserve the fighter's safety.
THROW IN THE TOWEL: When a fighter's corner feels their fighter has had enough and decides to end the bout for the safety of the fighter. This shall count as a TKO.
QUIT: When a fighter simply cannot or refuses to continue.
DECISION: When the bout has ended after the specified time period without a winner, the bout decision shall be determined by the three judges, as set forth by these rules.
DISQUALIFICATION: The fighter’s opponent is disqualified by the referee for fouls, use of illegal techniques or unsportsmanlike conduct.
LEGAL TECHNIQUES
HAND STRIKES: Fighters may strike with a closed fist to the body and face except to the front and sides of the knee, throat, groin and spine. Finger strikes or rakes are prohibited.
LEGS: Fighters may strike with their knees to the opponent’s legs and body (none to the head or face) when standing; they may strike with shins and feet to all parts of the body when the fighter is standing. No instep stomps or axe kicks to the head. Also, no kicks or knees are allowed to a fighter's head or torso when he is considered "on the ground" (i.e., when any portion of his body other than his feet touches the ring floor).
THROWS AND TAKEDOWNS: All wrestling, judo and jujitsu throws and takedowns are permitted. Fighters, however, cannot use spiking slams on their opponent.
CHOKES: All chokes can be done with the arms and legs. Grasping of the neck or throat with the fingers is prohibited.
LOCKS: Elbow, shoulder, wrist, knee and ankle locks are allowed. Single digit locks to the fingers or toes are illegal. Heel hooks or twisting knee locks are illegal.