The OP, I believe, was inquiring about situations where no weapon is involved.
Of course, it's a "no brainer" that a weapon of almost any kind, especially a gun, would automatically neutralize anyone in a street-fight............and end it in short order.
So I'll stick to the scenario's involving no weapons. Just "Mano'e'Mano.........
The best advice and instruction I ever got regarding these matters was from a retiring police major. We were working on his retirement home for about a half a year, so I got to talk to him a lot about this kind of stuff.
His basic take is that, usually if a fight is about to break out, or already has commenced on the "street" or in a public place, several things are about 100% certain.
1. The parties involved are irrational, unthinking, enraged and extremely emotional.
2. They're not going to be approaching the situations with a sound mind. So there are no "skills" involved normally in a street fight. Just rage.
3. The best approach, because folks fighting in public are out of their mind, is to use their own force and inertia and momentum against them. It's nothing but bull-rushing and wild swinging. Every punch or kick is intended for the jugular and to end it with one strike, because most folks want "out" ASAP.
4. So the first thing you do, is let them come at you full force, and then use one of several physical techniques to allow them to harm themselves. Steven Segal used this tactic as a primary weapon in his martial arts career. Just let the other guy rush you, and slap him out of the way. It won't take long before he's all busted-up and expired due to his own will.
5. Finally, YOU can't be accused of any malice if this approach is successful, because all YOU did was allow HIM to hurt himself.
Anyway, he was a police major for 30 years, so I believe he knows what he's talking about. That's how the cops are trained, so I put a lot of stock in this technique. Of course, some training on HOW to do it effectively is required, and he showed me at least a dozen different maneuvers that make it almost a total lock that you'll succeed using them.
He also showed me that move where, all you gotta' do is get your hand on the other guys hand and wrist, and IT'S OVER just like that. He taught me the move, and did it to me over and over and over again while teaching me. There's NO WAY OUT of it!! It's just TOTAL submission once this move is applied.....................