JLA: World Without Grown-Ups (1998)

The heroes of the DC Universe find themselves separated by a mysterious force in a miniseries that introduces DC's newest super-team, Young Justice! A boy receives a gift from his father and somehow triggers a force that puts all the humans 16-years-old and younger on one Earth and the adults on another. As the JLA searches for an answer to the mystery on one world, Robin, Impulse, Superboy and other heroes try to keep a kid-ruled world from falling apart. Does Billy Batson hold the key to bridging the two worlds?