"Supergirl" co-showrunner Robert Rovner said the tease was only supposed to air with "Flash"s "What's Past Is Prologue"; it was added to the other two episodes to make things easier for viewers because they "are coming to [the crossover] from our separate shows and we wanted something that [connects them together]". Stephen Amell announced 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. According to Guggenheim, by focusing only 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". "Legends of Tomorrow" was not included in "Elseworlds" to highlight the amount of time Amell, Grant Gustin, and Melissa Benoist could interact. "Elseworlds" returned to the episodic format of the earlier crossovers, contrasting with the approach taken with "Crisis on Earth-X". Rovner said, "It's like a three chapters of one story, but they’re all kind of unique to their own show"; "The Flash" showrunner Todd Helbing added, ""Flash" kind of feels like a "Flash" episode, "Arrow" feels like an "Arrow" episode, [and] "Supergirl" feels like a "Supergirl" episode". "Elseworlds" features Amell and Gustin portraying each other's characters. Gustin noted, "You’re not going to see me playing Oliver Queen's mannerisms, or Stephen playing Barry's mannerisms. It's more being aware that for some reason we’ve switched lives and destinies. It's more the fun of the situational comedy that we keep finding ourselves in, and less us having a complete role reversal." Amell added, "there are elements of his personality I have to embrace, and there are elements of my personality that he has to embrace" for Oliver and Barry to defeat the threat. Supergirl is the only other character who can see the true identities of Barry and Oliver; Benoist said, "She inevitably becomes kind of a middleman because ultimately there's conflict between the two and they start butting heads". Schwartz said "Elseworlds" would not "feel quite as dark" as "Crisis on Earth-X" and that there was "a lot more fun to be had" in "Elseworlds".