I am talking about mashing just Buttons not dp or fireball inputs. In generally is it possible to mash out a 3f punish? What is the proper mashing technique (on stick) to get fast speed?
You seem to be muddling your terms between your title and question. Are you asking if there is a mashable move (I presume you’re talking about SFIV) that works as a 3frame punish? Didn’t look but I’d say almost certainly not.
I was taking about fighting games in general. Say you block something that is -8 on block , and I have a button that has a 6 frame startup, can I punish by just mashing that button while I am in block stun? I cant seem to do it consistently, but I was wondering if i can improve my mashing speed via better technique or practice.
That probably varies more than you would think given different games having different input buffers. You will still have to time it to some degree because overly mashing will probably cause inputs to be lost to the buffer. You can try this thread for the windows.
for techniques you should look into double or triple tapping rather than a straight mash.
Well right now I been mostly play mkx, which has no input buffer while in block stun (unless it is a special move). That game has long block stuns so double tapping does not help much. Street fighter has short block stuns so punishes are easier. And then you have online lag variance which makes it even harder. Even a 6 frame punish I cant seem to hit without mashing?
It mainly cause I play online. So even if I practice the timing will be different online.
Well then you’re basically rolling the dice. MK doesn’t have good online to begin with. Sorry, can’t really help. The mechanics and design decisions of MK make no sense to me.