If it's that one cyberpsycho that crouches behind the broken car inside that yard and starts "teleporting" using cyberware - it's actually pretty trivial to beat him, IMHO. I had 3 points in Body and 4 in Reflex, and I fought him using an uncommon electric club at around lvl10, probably less. For all his "teleporting", after he gets close to you, he always does a completely telegraphed heavy attack which lasts for *ages*. In the end I just parried and got in 4 free hits. Rinse and repeat. He always does the same heavy attack if you get far enough away from him. I do have to admit that I gave him a cyberware malfunction at the start of the fight. It didn't last until the end, though. Just parrying consistently is much easier than throwing dozens of grenades at him, in my opinion (I was killed every time I tried being smart, and I didn't want to kill him, because quest).

And yes, System Reset rules.

I was having a hard time with the fights because I was completely ignoring Body for my build (cool/reflex/stealth/pistol). I didn't want to waste many upgrades in Body so I invested in some gorilla arms, that made the fights quite a bit easier.

Lol, this cracked me up, but yeah been playing for 30 hrs and the only time i was cussing at the screen was during the fist fights :P.
They are frustrating at first thats for sure, but after several attempts and rage fits, it actually starts to make sense and it aint so bad.
The fist fight quests are also marked as very high danger level, so you kinda know what you are getting into.

guys you can actually drop your melee weapon after the fight starts and then equip it, click on time and boom you can now beat the oppenent with ur katana/baseball bat

I only bought gorilla arms, they are not that expensive at all in the grand scheme of things. I won all the fights except one (including a hilarious one with a person I helped on a quest AFTER the main fight), and I'm guessing everyone know which one that is.

I only had like 7 body and I did not invest in any stamina upgrades.