I wish MK9 had Injustice's wake up system.
Invincibility and frame input windows are much tighter. I 100% agree with Tom that they should be practiced and you earn the wake up.
People having trouble doing inputs for special moves either during wake up or mid combos (trying to 2 in 1):
Try making sure the controller/arcade stick is at neutral before trying to do your next input. Dunno if this makes sense. Here I'll try to explain -
I'll use Joker for example:
after a b+3 mid combo I'll do d+2 (his uppercut) and 2 in 1 into teeth (qcb+3)
well when I do the d+2 and from there, while I'm holding the down input of the d+2, try to finish the qcb input...the TEETH DOES NOT COME OUT CONSISTENTLY. Sometimes I'll get nothing.
I'm using Alternate controls (SF inputs). So I'm not sure if it has anything to do with that.
But if I do d+2 > neutral (not having any directional input held or pressed) > then do qcb+3...I get teeth every time.
So if people are trying to mash things out, and everyone is guilty of that, either mid combo or trying to wake up...this is probably why your moves aren't coming out when you're expecting them to. Game has natural input delay. This is a way around it. I never had an issue with this in MK9...just saying.