Evidence is a few marks on the kids body to show you actually hit him, he was there and he cannot deny getting a black eye.
However, in the case of many against one, pepper spray works great.
That is if you don't know self defense. Or even if you do, it helps from them making a bruise on you.
However, I travel everywhere with a gun. Some would cringe at the thought, but here we are able to carry weapons on our persons and in our vehicles and its legal. There is a gun in every room of the house..just in case some fool tries to enter my home unwanted at some late hour. However, I do know self defense as well. But, why ding myself up when I can use something else to deter the intruder or mugger and prevent further incident to myself or to protect other innocent people. Probably more arguments from those who hate guns, but it is just I have had extensive training with weapons so it benefits me to have them handy.
Yes, some are not threatened by guns when they have several themselves. Such as the gangs in Chicago, which I have had an encounter with over an old girlfriend in the service. Somehow she got on a date with one before I met her, but they were not going to let her go so easily. Anyway, it took a little more than a gun to settle the dispute. I needed an Army of men, which of course friends are good for that in the service. However, nobody was harmed and the gang left her and her family alone. It was a close call. But it was needed to protect her and her family.
Now, to say if I saw a mugger on the street mugging some woman or other helpless man, I would probably most likely use my body as a weapon instead of a gun, unless he had a gun, then it would have to be the choice to use my gun to defend all on the street including myself. Now if its just a man beating up his wife, then there is no reason for any weapon, just a nice knock along side his head and maybe a little torture from me and of course me holding him down for her to beat on him for a while before the police arrive..of course all in the name of self defense..of course.

Mostly it would be because I can't stand to watch any woman get beat up, even on a movie it disturbs me and angers me. It might be considered excessive force, but usually the police take a while to get to the scene so there is time to make sure the woman gets her revenge on the man who beat her up and of course the truth is she was defending herself..as it would be testified in a court of law. Justice is sweet.