From my matches with admiral augustus, quan chi can be deadly. Main strings are B3 1+2, which hits low then overhead. It's very easy to block this string, but it is safe on block. He has another string that starts mid then hits low, you've probably seen it, where the string ends with him smashing a skull to your gut. What you want to do is to block low pretty much all the time, most likely he will connect his strings with mind control which is very punishable. So long as you know his mixups, quan chi becomes very easy.
But there's also the dreaded U4, which hits overhead and can be linked into mind control. If they start using this, be prepared to block high. It's unlikely they'll use this twice in a row because they'll assume you'll be blocking high the second time around. The good thing is that when using U4 it needs to be committed to mind control, there's no hit confirming.
Quan chi's rushdown is inferior to johnny cage's, and he has no "get off me" moves at all. You can snuff out the teleport easily, especially on wakeup where all you need to do is cross over and low poke. Eventually he'll learn that he'll have to poke back or eat JC's ridiculous strings.
Also try not to get caught in the rune trap.