They did it First.

[daBronzeBomma]

Toyman just needs giant toys to threaten Metropolis and he's fine as a lower-level Superfoe. Or just give him wholesale over to Supergirl, she could use some rogues that are more her own.

Prankster's the harder nut to crack. I just don't see any place for him as a direct foe for Superman: Prankster's basically a cross between Luthor and Joker, which in theory would make him as awesome as those two superstars, but instead makes him less than half as impressive.

I'd say make Prankster's primary vendetta against one of Superman's more vulnerable human companions: preferably Lois or Jimmy. Love the "absurd hacktivist" idea, btw. That's a great angle.

[Grim Ghost]

I might re-imagine the Prankster as a Jackass style Johnny Knoxville kind of character, but a dangerous one. A guy who puts himself and others in danger through extreme pranks to get himself attention and pull off crimes. Maybe he isn't out so much to defeat Superman as to simply make him look foolish. Maybe add a touch of the bronze age Joker to him as well.