Well, you have to exploit the fact that his moves have a very slow pullback. This is best done with the second air jump to get out of the way, and then dash in for some heavy damage. Ciel is good vs Nero because she can dash under his projectiles. Arcueid is good too because her elbow dash breaks almost all of nero's moves. The thing with the mantis arm is just what I said above; the pullback time is sick. Even if you do defend it you probably have the time to dash and get an OTG-attack (or whatever it's called
) on him. Some characters, like Sion (normal) can counter his normal moves with her "dragon punch" move. It will break all his moves I think.
Ah, and Warcueid and Waracia are probably good too, since they can teleport behind him as he uses for example the mantis arm.
Oh, I got another one! I got another one!
Kohaku kicks his ass with her supah hard air to ground attack and her supah long OTG-attack