Not sure what you're referring to when you say "camphing" but you can play Nightwing in Batman: Arkham City though it must be purchased as downloadable content. Also, Nightwing is only played on the Riddler's challenge maps not in the main story itself. The same applies to the Robin DLC.
If you want something with more story, Catwoman's DLC ties into it and has several campaign episodes.
Hope this helps!