Grendizer: Getter Robo G - Great Mazinger Kessen! Daikaijuu is an anime film that premiered in summer 1976.

About the production: the film runs about 31 minutes and its current status is "finished".

Its main genres are adventure and mecha, with themes such as Super Robot, Kaiju and Crossover.

On AniList, Grendizer: Getter Robo G - Great Mazinger Kessen! Daikaijuu has an average score of 59%, an average score, and appears on 1,135 users' lists.

A giant sea monster known as "Dragonsaurus" has emerged from out of nowhere, terrorizing the depths of the oceans. Great Mazinger, Grendizer and the Getter Robo G team join forces to combat the new threat. But their task becomes more complicated when Dragonsaurus swallows up Boss Borot and makes its way towards Tokyo. (Source: Anime News Network)

Official synopsis from AniList.