Few key things to remember in this match.
You only have to respect his EX Ground spark on block, as he gets a free ground spark afterwards. (Staff stance)
On block from a regular ground spark, you have to jump or dash or else you will be hit by another ground spark, if you jump they can do an almost full screen greyson.
About the Greyson, it is -3 on block, so if you are a character that has a good d1 game, WW, Doomsday, Nightwing, Green Arrow, etc, then you can always d1 them before they can mash their D1's, as long as you have an 8 frame or faster d1, you will always out beat them.
On wiff, it is full punishable, but you have to crouch and then instantly punish it.
His D1 game doesn't need to be respected as much as you think, it isn't a matter of his d1 being + on block, its a matter of how many d1's he will do, he has to commit to a normal attack eventually, so don't sit in crouch all day respecting it or you will get hit by NJ2. You can full combo punish Nightwing players for not hit confirming 1F1 EX ground spark, that can be interrupted.
Its only a match up that causes major problems when you don't know what you can do in it, and most of the nightwing players out there are just doing what they want because people are not punishing them.