I wish everyone would aknowledge that Flash has never actually hit anyone with an ACTUAL INFINITE mass- he's hit a Martian at very high mass, but Morisson never stated that he had Infinite Mass. If I remember correctly, Wally refers to himself heading to towards Infinite mass - therefore still has some way to go. If he was at Infinite Mass he would have said "My Body is at Infinite Mass".
Morisson (Who created the scenario in question) on the whole has a very good grasp of real world physics, you can tell by his useage of it in various of his stories (The one when he uses the wierdness of qunatum mechanics as a backdrop for a JLA story comes to mind),
-and he makes it very clear through out his Flash run (Which he wrote at about the same time as the Martian storyline), that when a Flash goes faster than the speed of light, he ends up in the Speed Force. Therefore Wally was not travelling at F.T.L. when he hit the Martian,
So inconjunction with the FACT that he recognises that one would have to be going F.T.L. to have an actual Infinite mass (And he does recognise this !!!!!!!!!), Wally didn't have Infinite Mass, and to my knowledge the Infinite Mass Punch has never been utilized since, with the exception of Zoom who also never stated his mass to be Infinite !!!!!
Hal Jordan as Pharallax; KO'ed Superman with one hit ... I don't think anyone else has ever done this. Thats not to say that others couldn't, but many have tried and Failed:
Captain Marvel (Ko'ed Superman but it took three hits)
Superboy Prime has yet to KO him with one hit.
Orion and Darksied haven't even come close.
His Earth 2 counterpart didn't even come close.
Kingdome Come Superman didn't Knock him out with one punch.
Doomsday has never Knocked him out with one punch.
Don't forget this is the guy, who Brainiac had to blow up a Sun to KO, and is only found unconscious when some planetary mass of some kind has been destroyed.