The best form to avoid harm to all involved is Aikido.

http://en.wikipedia.org/wiki/Aikido

Most martial art forms are designed to incapacitate the opponent or otherwise meet the attacker head on. Aikido focuses on simply not being there. The first reaction to a fight we learned in class is to walk away. The second is how to fall safely (rolling and rocking instead of slap/falls).

Aikido teaches its students to use circular motion and an opponents momentum to anticipate an attack and ultimately redirect the force of the attack into a harmless result.

The most successful at practicing this art can achieve a subdued opponent with little effort. Redirecting the force of the attack in the direction of the defenders choice (with no grip required), even putting two opponents at odds with each other leaving the defender free to run away while they disentangle themselves.

http://www.youtube.com/watch?v=sJ8VLPPTuH0

Early practitioners of Aikido thought themselves invincible. Proving their prowess against guns (and failing) utterly confused them.

There are "hard" forms of Aikido that involve stiff arm strikes, staff and katana. The "soft" forms teach us how to redirect an attackers motion into positions where they can be gently held harmless until help arrives.

Aikido is most effective against group attacks. Free form practice at the dojo is sometimes complimented by every student attacking the teacher at once. Sometimes the teacher actually allowed himself to be thrown because the position gained actually threw him clear of other attackers and he could move away.

During a golden moment in my own training early on I succeeded in avoiding an attacker by redirecting his momentum with my chi - no physical contact. The move resulted in my opponent being thrown (yes, thrown) past me and I was free to move away untouched. I was chastised for practicing a technique that was beyond my training at that time. (I'd read about the technique and had wanted to try it.)

The origins of Aikido are attributed to Morihei Ueshiba who was not healthy enough to practice traditional art forms. I have asthma and was never very fit so this form (along with it's philosophy and soft form) was a perfect fit for me. It also works well in close quarters and against opponents that are larger. The stronger the attack the more effective the redirect. Simple holds and grips keep the opponent off balance or pinned and unable to respond with more violence.

Someone asked me once if I thought Aikido would win against Bruce Li. Since a practitioner of Aikido would never challenge someone to combat and Bruce Li would immediately recognize the futility in pursuing someone who didn't want to fight (always moving out of the way) I had to give a qualified yes. More accurately it would be a draw but if pursued I think that Mr. Li would have found himself rendered harmless more often than he connected, but only against someone skilled in the art.

I'd say aikido, it's a defensive sport where you use the power of the attacker against him by 'steering' it's power elsewhere (to the ground and such) or disarming an attacker

I would say mostly any Martial art would work, as long as you use basic techniques. For Example, I'm currently learning Taekwon Do. As long as you use something simple, like grabbing their wrist an twisting it slightly would work.

All martial arts would fall into this field actually... what is more important is the person using the martial arts and their understanding of their craft. The more an individual understands/respects their form of martial arts the better they can control their actions. This in turn allows a martial artist to defend themselves using the attackers force against them, which results in less chance of injury.

My personal choice would be Tai Chi if I had to pick a specific form, as its focus is on inner focus and slow movements (though once quickened these movements are still just as useful and dangerous).

In the movies, fights are done with fists and feet. If people are boxing with some sort of rules in mind, this can happen in real life. But in real life fights, usually people end up on the ground in the first few seconds of the fight.

For this reason, In real life, all fights end up on the ground in a matter of seconds. Learning how to defend yourself and subdue an attacker on the ground is the most important thing you can learn if you're ever in a real fight.

This leaves you with a few styles worth learning - aikido, hapkido, and judo. Judo is an olympic sport that gives you a lot of opportunity to spar and fight in practice, but has the disadvantage of having a structured rule system, which of course will never be followed in a real fight. Hapkido and Aikido are a little more free formed, but still teach you a lot of grappling and submission techniques.

Unfortunately, I think most fights tend to end with somebody being injured. The face can't take a bare fist without getting broken somewhere, and a fist usually can't take a bare face without getting broken somewhere. Boxing gloves are there to protect your hands. Without gloves on, you can't hit somebody hard in the face without hurting your hand.

On top of that,big people will beat up on little people almost irrespective of fighting skill. The Jackie Chan type little guy defending himself against the bruising thug is a movie myth. The little guy is going to get clobbered 9 times out of 10.

And if there is a weapon involved, forget it. The one with the weapon is probably going to kill the one without. I used to spar with fake knives when I used to do Wing Chun Kung Fu. No matter how skilled my opponent was, I had no trouble cutting him, and he had no trouble cutting me.

So if there is a message here, it is to do martial arts for fun and interest. The best way to protect yourself in a fight is to run, and if not that, have a weapon. If somebody really wants to fight you, its your job to protect yourself, not worry about his health.

I have been taking Tae Kwon Do for amost 8 years, and our school focuses on self-defense techniques. We work with little kids all the way up to Adults, and we try and use simple joint locks, and basic strikes. Joint locks (as shown above in a the video) allow you to control your attacker without seriously hurting them (unless that becomes necessary). Most are designed to go at the wrists, or arms because these are the main things people use for attack. If someone is coming at you kicking, you are more than likely going to end up fighting not just controlling someone.

There are many schools of TKD out there, some teach self defense, some just teach sparring and some are black-belt mills. If you are serious about learning how to control someone without hurting them, look for a school that teaches self-defense and isnt just there to take your $ and promote you to black belt. there are a LOT of great schools out there, and some in places most people would laugh at (IE YMCA's).

The thing that you have to understand is that all of these forms of Martial arts require one major thing.. TIME, you need to work on techniques over and over and over (1000x1000?) before they start to become reflex.

A lot of people think they can take 1 class somewhere, and they are masters at the techniques at the end, this is not the case (unless you are some kind of prodigy).

The most important part of a good Martial Arts class is the attitude of the instructor.