Not sure what I'm bidding on, but:
Megalodon vs. Batman
Probably one of the Megalodon's most formidable opponents, Batman, secretly known as Bruce Wayne, or more formally as the Dark Knight, is a night-dwelling vigilante whose home is based in Gotham City, New Jersey. The advantages of this Caped Crusader are his sheer wealth and ability to maneuver himself out of any situation using shiny black accessories and his unmitigated wit. But it's not all primitive instincts with this man, as he is also a pioneer of intellectual prowess and eventual personality development.
The Megalodon may bite off his bat-ears, but in a swift and jet-like motion, Batman would dive face-first into the shark's mouth and take on his enemy from the inside out. Using grenades and bat-shaped shakrams, Mr. Wayne would dispatch of the Megalodon faster than Kanye West could rip Taylor Swift's mic out from her hands. Batman was clearly not present for the Video Music Awards that night.
Conclusion
As is the case with most hypothetical musings, we cannot be sure of most of these match-ups. What we can be sure of is that the Megalodon would undoubtedly trump most all opponents, shy of one: The Batman. Because of the possible existence of such terrifying monsters of the night, it is with certainty that we can conclude this: Batman is not the hero we deserve, but the hero we need.