If you get punched in the nose your eyes will water, a lot, even if it didn’t really hurt
Your body follows your head, your head gets pushed one way and your body will want to go that way
Getting hit in the stomach isn’t good, it hurts, getting hit in the diaphragm is worse. Causes your lungs to kinda spasm and make it hard to breathe (diaphragm is between stomach and chest)
When fighting a larger person they will have an easier time forcing you back
The jaw is the knockout button. Hit it hard enough and down for the count
Back of the head is very vulnerable, can cause serious damage if hit there
Kidney punches. They hurt. A lot.
People with experience will try to be where they are comfortable. A wrestler will try to get their opponent on the ground, a boxer will stay on their feet, etc.
Easiest counter to a kick is to get closer to whoever is throwing it, then they won’t have enough room for it to be effective
If you want realism, avoid fancy, flashy moves. They’re less practical and easier to counter.