Originally Posted by
Doctor Bifrost
Of course, there is one more way to handle the JSA/II problem, which DC has sort of used before. The JSA starts in WW II, many survive, their kids get started as Infinity, Inc. around 1970.
Then, around 1972, before Superman and Batman come on the scene (I'm assuming Wonder Woman was in the JSA), there is a Crisis. A Very Powerful Entity gathers together a bunch of superheroes (including most of the JSA and II), some of their spouses, and a whole lot of their most important villains - for reasons that are Very Important To The Plot -and puts them to work, or to the test, or whatever.
At some point in the conflict, the vast majority of these characters wind up trapped in timeless void (or a magical amulet, or an enchanted bottle, or whatever) where they are essentially in suspended animation. But not all the characters - Wonder Woman gets left behind, and maybe a few others. (It would be interesting, for example, if the GA Wildcat and his son are left behind; in the current day he's died, but his grandson is active as a superhero. Or maybe the Martian Manhunter came to Earth in the 1950's, long before Superman and Batman became superheroes, and continues to this day. Choose carefully.)
And no one is able to find the lost heroes, or even demonstrate that they have not been utterly destroyed. (But the world still remembers them. None of this "everybody forgot they ever existed/now suddenly everybody remembers!", which is one of my least favorite comic book tropes ever, for a number of reasons that I won't go into here).
At some point in the current era, probably after Superman and Batman have started up and the JLA has been founded, they are found! And/or released. And/or returned. It'll be a Really Big Story. And then they can continue their lives - with the JSA heroes a good deal older than the JLA heroes, and Infinity, Inc. in full swing.
It's hard to do this in a way that doesn't come across as conspicuously (rather than just ordinarily) contrived. And in may opinion you wind up with far too many characters with the "fish our of water" time-jump aspect, which can get a little redundant. But it can work.
Marvel did something like this, with a bunch of previous-era heroes trapped in an urn. But I wasn't reading them at the time, and - despite my Google Search talents (he said modestly) - I haven't been able to find it. Can someone enlighten me? Was it in mainstream Marvel continuity, and are the characters still running around today?