Great Mazinger vs. Getter Robo is a short crossover film featuring the super robot highlights of 1974, Great Mazinger and Getter Robo. It is the first in three short films that utilize the robots of Dynamic Productions for a crossover film.
A mysterious UFO has been spotted over Japan and both the Science Fortress Laboratory and the Saotome Institute wish to observe it. Due to rivalries between labs, their representative robots Great Mazinger and Getter Robo compete to see who can get to it first. The Getter manages to get to the UFO first which is revealed to be semi-sentient and attacks the Getter before releasing the bio-monster Gilgilgan to conquer Japan. Gilgilgan's ability to eat metal allows it to easily defeat Great Mazinger. Despite the protests of the pilots, the labs decide to team up as Gilgilgan becomes more powerful. Using the robot Boss Borot as bait to lure Gilgilgan to a deserted island with no metal (yet Boss Borot is eaten), the Great and Getter prepare to fight it and manage to defeat Gilgilgan. However the UFO comes back and allows itself to be eaten for Gilgilgan to assume its ultimate form. Gilgilgan overpowers both robots but the labs identify its weak areas and instruct their pilots to strike those areas destroying Gilgilgan. At the end, the pilots leave on good terms and promise to be friends.