In the 1966 "Batman" feature film, The Joker, the Penguin, & the Riddler joined forces with the Catwoman. 2 years later, Filmation brings the fiendish four together again in "Partners in Peril". Ever wonder if Ted Knight & Casey Kasem were getting paid extra for all the vocal gymnastics they had to do in this one?
The cliffhanger format used on the live-action show was employed for 2/3 of the 30 minute cartoon each week, and after the conclusion of the longer episode, there'd be a short to close the show. "Partners", however, would make a good test case for a full-length episode, the format favored in the 1977 New Adventures series, as it would make the plot a little more sensible.