I want to be a bit more elaborate
i say again, it's Prof Barry Elkin.
He apeared only ONCE before, in a comic with superwoman (Kristin Wells) since he is her boy friend
http://superman.ws/Maggin/superwoman.php
The clues are there:
-the emphasis, that some1 affliated with the S symbol (by luthor and WG, and the fact that superman wore that name once)
-similar power
flying and teleportion (who would gibe a superhero both powers),
precognition (explains his sharp senses)
-similar costume (the hood cape)
-no records of supernova (normal for illegel time travelers)
- booster gold kicked his butt, which means no invurnability
-he knows where the batcave is! knowledge he brougt from the future
AND knew that luthors kryptonite glove was stashed there!!!
-superhero experience
well he slept with someone who specialised in superhero history.
so he caught one or two things ....
WHY?
well his motivation lies in the fact, that superwoman/ his grilfriend was erased from the DC continuum.
She was supposed to (precrisis) make several stunts like fighting alongside greenl lanterns etc. then return to the future and tell her boyfrined about her adventures.
but since all this never happend, there was also no reunion!
So time is broken perhaps to fix this and bring her back ...