On Planet Zi, in Blue City, a boy named R.D. works as a delivery boy for the Mach Storm team; he pilots his Liger Zero to help with his job-related tasks, but often finds himself in the middle of a Zoid battle as well. However, R.D.’s personal mission is to find the Alpha Zoid, the legendary machine that his father spent his lifetime trying to find. Along the path to fulfilling his dream, R.D. must deal with rivals such as Blake and the Savage Hammer team, and also somehow figure out the secrets of the Fuzor Zoids!
Both of these anime are about individual mecha fusing together to become more powerful, and there’s always an expected battle each episode. Another similarity is when certain, unfortunate conditions are met during combat, the union of the mecha will fail and result in its separation; and in order to perform the union in the first place, there are also prerequisites.