Both Captain Atom and Martian Manhunter have been portrayed as league busters, but than Zod owned MMH in a rush. Okay MMH gaurd was down. But, Atrocious took on Manhunter and Appollo and Midnighter, only to later lose to Guy, of course there was some history erasing involved in between. And something happened to Atom, so the future where he takes out the Legue never happens. But man hunter did still take on the legue, Zod took him out, wonder women held off Zod and his girl for a while, so superman could stop crying, so she is the most powerful! Except Aquaman knocked them around as did his brother (who Aquaman also beat) so he is the most powerful, except MMH took on the whole Le- .... Err wait!
I'm just going with Jimmy Olsen! How he managers to never get a good picture of superman and still keep his job? Completely over powered! Though I could see a case for Batcow!