User blog comment:Ultimate Heatblast/Wanted Characters/@comment-96.254.92.224-20120424014633/@comment-1038387-20120424185449

Four times.


 * The DCAU had him as Nightwing in The New Batman Adventures.
 * The Batman featured one dystopian Dark Knight Returns-esque episode ("Artifacts") with Dick as Nightwing.
 * Teen Titans had him as Nightwing in the future of "How Long is Forever".
 * And in Batman: The Brave and the Bold, he became Nightwing at the end of his debut episode.

Though technically, only the first and last of those showed a transition (and the DCAU only in flashback and tie-in comics), and I'm not counting Batman: Under the Red Hood.

I think it's absolutely unnecessary to do it on YJ. It would serve little purpose other than making fangirls/boys squee. When that happens, the plotline usually suffers.