Technically, Robin should be Nightwing in Crisis.
The synopsis for this issue has not yet been written. Batman '66 Meets Wonder Woman '77 #5 is an issue of the series Batman '66 Meets Wonder Woman '77 (Volume 1) with a cover date of July, 2017. It was published on May 24, 2017. Featured Characters: Batman (Flashback and main story) Nightwing...
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To be fair, 2019 is a long time in the future for when his late appearance was. We don't even know what his role will be, it might not even he related to the 66 version, those it most likely will be.