Muteki Choujin Zambot 3 is a tV series anime that premiered in fall 1977, produced by Sunrise.

About the production: the story comes from an original script, there are 23 episodes of about 25 minutes and its current status is "finished".

Its main genres are action, drama, mecha and sci-fi, with themes such as Aliens, Super Robot, War and Kaiju.

On AniList, Muteki Choujin Zambot 3 has an average score of 68%, a good score, and appears on 4,472 users' lists.

There once existed a planet named Beal, until it was wiped out by the mysterious entity known as Gaizok. The few remaining survivors escaped to Earth and split into three families, named Jin, Kamie, and Kamikita respectively. While attempting to start a new life, the collectively known "Jin Family" prepared for the inevitable Gaizok invasion on Earth and its giant mechanical beasts known as "Mecha Boosts". In order to defend their new home, they have built three vehicles which when combined form the mighty Zambot 3. The Jin Family must not only defend against Gaizok attacks, but also harsh criticisms from the very people they protect, who blame the Jin Family for the invasion in the first place. (Source: AniDB)

Official synopsis from AniList.