Stephen Amell revealed that, unlike previous Arrowverse crossovers, this one would not be as extravagant, but more about "the characters and the story", focusing on Green Arrow, Flash, Supergirl, Superman, and Batwoman. Guggenheim felt by only focusing on Green Arrow, Flash, and Supergirl, the writers "really had a chance to tell a story about the troika that we’ve never really been able to do before." This was one factor to why Legends of Tomorrow was not included in "Elseworlds", to highlight the amount of time Amell, Grant Gustin, and Melissa Benoist could interact. "Elseworlds" also returns to the episodic format of the earlier crossovers, unlike the approach taken with "Crisis on Earth-X". Rovner explained, "It’s like a three chapters of one story, but they’re all kind of unique to their own show," with The Flash showrunner Todd Helbing adding, "Flash kind of feels like a Flash episode, Arrow feels like an Arrow episode, [and] Supergirl feels like a Supergirl episode."
--Wikipedia