Zas can also punish NM well with WS B or WS K when he ducks things like GS A, GS KK, agA, 6K, NSS K etc. If the second hit of GS KK is ducked at the edge of the ring, 44B4 = ringout (yes, I know this is very situational and rare.) Zas has a great interrupter in 4B which scores a CH just for NM being in GS. Thats 58 damage + great followups. 6B+K on block doesn't whiff against NM like it seems to on so many other characters :/
Nightmare's 11B is pretty easily stepped to it's left, and if its blocked, Zas gets a free 2B4 from most ranges to pull NM inside. Zas' 1A on the other hand tracks 100% and can be mixed with 1AB for jumpers (may have been its true intention as nobody is ever really hit by 1A in open space). 1AB is not easily punished by NM and at max range, blocked 1AB doesn't even give NM a proper FC mixup because he is out of WSB and throw range.
33B is a good tool to use from range once an a while and its only -5; I believe the pull is -10. iWSA/iWSA4 is also useful as it is very fast for it's range, has extreme range, gives great advantage, tracks to both sides, breaks the SG in 15, and both versions are safe vs NM. So Zas does have a few options at that range, but the idea is to bring NM inside anyway.
What tools does NM have to deal with Zas when Zas has advantage in his face? 6K? 1K? Only to keep him honest really. I get that NM has overall better damage output, but I could actually see this being 6:4 for Zas. It's at least 5:5 IMO.