Meghan Fitzmartin

The Justice Society of America , a group of heroes aiding the allies in World War 2, acquire an ally from the future who sends them on an adventure that changes history. (imdb)

Superman, Batman, Wonder Woman, Flash, Cyborg, Green Lantern and Vixen are transported to the strange world of Remnant and find themselves turned into teenagers. Meanwhile, Remnant heroes Ruby, Weiss, Blake and Yang must combine forces with the Justice League to uncover why their planet has been mysteriously altered before a superpowered Grimm destroys everything. (imdb)

After their adventure in Remnant cyberspace, courtesy of Kilg%re, the Justice League returns to Earth. However, they find the Grimm have followed them and are somehow duplicating their powers. Bringing Black Canary up to speed, the League is forced to seek out Team RWBY for help.