Re: Justice League Vs Avengers
in the Superman/Batman books (the new ones) Superman carries Darkseid from the Kent farm to the sun in about 2 seconds. I bet you can find about 8 billion comics of the current "continuity" that don't have him anywhere near that fast. Changing levels for story telling isn't lazy writing... you put the character where you as a writer see him or her. For example, some people would have Supes as a character who is equal to a GL, Thor, etc... while other writers set him at different levels to tell their stories. For example...
In an interview with Joe Casey on Alvaro's ComicBoards, he stated that Superman under his penmanship could re-arrange the Solar System and tear a star apart. "I've always seen Superman as this completely over-the-top, fantastic character who has *no* limits whatsoever," said Casey. In Superman's probe-busting mode, "Superman is unbeatable."
Now, there are plenty of writers who don't see Superman as unbeatable no matter what. The Death of Superman certainly didn't see him that way... or maybe they did, as he was resurrected and defeated Doomsday in the long run. Frank Miller agreed with Casey originally, but his final draft of DKR was different from the original and had Supes beaten by Batman, Robin, and Green Arrow. Now I know that's "out of continuity" but it all depends on where people see the characters. It's not power levels that are important at all... it's the character and how you use him or her to tell the story. Sometimes Spidey can beat up Venom. Sometimes he can't. Sometimes the Juggernaut is unstoppable. Sometimes Hulk stops him. Whatever story somebody wants to tell is more important than set power levels. With as many "current continuity" books as there are out there, it's impossible to say there really is any continuity because they contradict each other so much. But ya know what... that doesn't matter at all because story telling is by far more important than power levels and stats. I'm a huge fan of a lot of different characters and the power levels mean nothing to me. If you make Superman a complete wimp, I think that sucks because his character revolves around him being the top dog. If you make Wolverine team captain and a gentleman, that betrays his character... not giving him a slower or faster healing factor. I do think that if there had to be set power levels, it would fit in the Marvel Universe but probably never in DC. DC is it's own mythology and mythologies have numerous interpretations of each character.