I agree with this whole post.
Some help for my NM would be appreciated. I'm ok with him but against good players, I just get smacked around.
If it helps, you're pretty decent. Didn't see you do anything way wrong. That said, I've got three points here:
1) This is the biggest one, you need to work on your just frames. iagA is annoying shit to do, and will come to you with practice in due time. You need to focus on 3(B) NSS b:A. That just frame is hugely important to Nightmare's damage output. You were landing so much 3(B) in those fights but I don't think I ever saw a b:A just frame. You need to start making this happen just based on math. More than 1/3rd of their health gone (240 ÷ 75 = 3.2) from a two hit combo, in addition to CRAZY ringout distance
and a wall splat on the easiest just frame in the game. It is literally the best thing about Nightmare.
2) vs. Pyrrha, she had a huge BB whiff right at the wall and you went for a throw. This is the only real "mistake" that jumped out at me. Need to get 3(B) into your muscle memory on whiffs.
3) More single 3As. It's unsafe by itself, but most people expect that second hit so they don't punish/take advantage. If they start reacting, the second hit of the string can't be interrupted. On CH from a single 3A, you get a hitconfirm into 3(B) NSS~GS into shenanigans. 3A mindgames = good spacing. Really helpful at keeping Greeks the fuck off you. Since if they're expecting a mid stepkiller with a reward on run counter, they'll have to think harder about tech crouching in through your spacing and that makes (i)agA a little easier to get away with.
You know, seriously, you're on your way with Nightmare. You were doing most things right... Your movement was pretty good. I'd say you handled yourself very well for him not being your main vs. a good opponent who threw 3 of Nightmare's 5 worst match-ups at you. If only he played Patsuka and Pyrrha Omega too. Goddamn.
Keep it up, get them JF slides down, mainly b:A. You'll be on the level very soon. I'll rewatch the video at some point today and see if I can be more helpful.