Well, I have to admit, I'm a fan of both Ed Edd n Eddy and Transformers, and there were several YouTube videos that have elements of both the two franchises, but I would like to have my own idea of what an Ed Edd n Eddy/Transformers crossover would look like:
In the beginning of the crossover, the three Eds have engaged in space combat, shown by parodying space battles from Star Wars as well as that of American space launch footage. The three Eds' spaceships look like a cross between a TIE-Fighter and a Vulture droid, both from Star Wars. As they were fighting, the three Eds somehow have crash-landed onto a planet resembling Cybertron. The Eds soon learn of the transformable robots that have been on the planet, and when they meet Optimus Prime, they promise to help them no matter what, due to the fact that the Decepticons were planning to conquer New Cybertron. The Eds would also build their own robots for use in combat.
However, in the middle of the crossover, the Eds have discovered a giant robot that plans to destroy the planet. The Eds and their pals from the cul-de-sac try to do whatever they can in order to help keep the planet safe, mainly using space combat, with the help of the Autobots.