Paul Dini reveals that he really wanted to make an episode of Batman: The Animated Series that just focused on Catwoman and Black Canary, but the idea was stopped by an executive mandate.
Talking with Comic Book Resources, Dini reveals that the episode pitch was rejected because there wasn’t enough of Robin in it:
“Yeah, the Black Canary/Catwoman episode was a casualty. They wanted more Robin in the series, and each time we wanted to drop him from a story, we had to fight for it. Not that we had anything against Robin, we just wanted to stretch now and then and do solo Batman stories or episodes that focused mainly on Gordon or the villains. After the experimentation of the first season, the network felt we might be leaving the boys behind, so we got the edict, add more Robin.”
Black Canary would eventually be introduced in Justice League Unlimited series years later. Dini also revealed that he had an idea for an episode where Poison Ivy sought out the attention of Swamp Thing, but this didn’t happen for a reason that didn’t involve an executive decision:
“There was a Poison Ivy seducing Swamp Thing story I toyed around with, but the rights to Swampy weren’t available then. I did a sort of version of it years later as an episode of Justice League Action.”
Batman: The Animated Series is available on home video formats.
Source: Comic Book Resources