So if you don't teach them small guns, but reverse-pickpocket guns and ammo on them, they'll all just run away from any fight?
No, some will fight but others will run.
Kimba, for example, will not fight unless you taught them small guns.
My advice?
Visit minefield first. Collect all the mines.
Then, set up the minefield on the road leading to bigtown, to right of its bridge entrance. That's where the SM attack comes from. Then do the quest and teach them to use small guns. They'll all get a weapon and learn to shoot. Then the mutant attack comes. The mines should kill most of the mutants. You can help them finish off any who get through your minefield.
Then you can pickpocket arms and armor on them as you see fit, if you hadn't done so already.
For fun, you can kill the baseball bat wielding raiders at the nearby baseball field, and drag their bodies in front of big town. Now whenever they respawn they'll attack big town and be quickly dispatched by the gun-toting big towners.