Maybe Gingerboi123, you have the boxers rated with so many offense and defense points then they can execute the fight using these basic moves with what ever point system you decided. 

Basic Strikes: 

JAB
STRAIGHT LEFT/RIGHT
LEFT /RIGHT HOOK
UPPERCUT

Basic Defenses: 

PHYSICAL DEFENSE
Advantage:
Easy to do. Requires no skill.
Works well for beginners.
Very effective for blocking entire combinations.
This defense protects you against any style of opponent.

Disadvantage:
Can block your vision from tricky punches.
Not easy to counter-punch from.
Can be tiring to hold your hands up all the time.
:
COUNTER DEFENSE
Advantage.
Allows you to be more offensive with less worry.
Improves your counter-punching ability since you know what to expect.
Saves energy since you are only worried about blocking specific punches.
:
Disadvantage:
Will not help you against tricky style opponent.
Can make you vulnerable against tricky counter-punches.
Requires you to be more alert.
Requires you to use your memory or train until your counters become a natural reflex.
:
AWARENESS DEFENSE
Advantage:
Allows you to box against higher level opponents.
Allows you to defend against trickier opponents.
Allows you to see more since you use your eyes for defense.
Gives you more offensive and counter-punching opportunities

Disadvantage:
Will leave you dangerously vulnerable when you are tired or lazy.
Requires the most energy, physically and mentally.
Requires the most skill.

Have the fighters choose which style of fighter they are as well.

1) Brawler. This type of boxer will generally throw single and powerful punches against their opponent. A lot of brawlers are able to throw a punch which can knock out an opponent in a single blow. The biggest problem with this fighting technique is how slow the boxers usually are to punch. By being so slow they can be countered a lot more easily.

2) Inside Fighter. This type of style is usually played very aggressively and incorporates an "in your face" type of play. The idea is for the boxer to get and stay close to his opponent and knock him out with multiple fast punches. This is a great class to be used by medium weight boxers.

3) Outside Fighter. Boxers who use this style type will generally stay toward the outside of the ring and work on keeping their opponents away from them. The idea is to wear out your opponent rather than knock him out. This style is usually played by lighter class boxers who don't have the strength for heavy punches.