Pfft you cant handle Green Sexy. But yes Nightmares wall game and ring out game are top bloody notch. You should see the wall combo i discovered the in the "favourite combo" topic or something, 150+ guaranteed dmg = HELLO!... and thats without tech traps.
But then Taki and Amy have a lot better advantage in normal play, like they have some pretty good wall combo's but not nearly as good as Nightmare. But Nightmare has really crap attacks, only a select few which are safe, unlike Taki and Amy, so its just personal preference man. He is pretty much a beast at walls and ring outs and also some damn good pressure and some nice mix-ups.
But he is easily outclassed if 2 opponents are in the middle of the stage... but that dont happen , cause Nightmare will put his rape face on and send them flying back!
P.S. Yes you did get raped by me :P. Oh but yeah if you get a mic, i will be able to help you if you decide to pick up Nightmare! Or give me your paypal and i will buy you a new mic -_- seriously lol.