A pair of twin boys named Mars and Marg were born long ago on the planet Gishin. Emperor Zool took the one named Mars as a baby and sent him on a mission to Earth. This mission was to detonate the bomb inside his robot Gaia and destroy the planet, aiding in Zool's quest to conquer the universe.  Mars was adopted by Earth parents and grew up having a normal happy life, not knowing anything about his origins. His parents named him Takeru, and as a young man of 17 was a proud member of the Crasher Squad, helping the Earth in their space exploration program.

One day, the Gishin came to Earth and told Takeru about his past. Loving the Earth, Takeru rejected Zool's plan and instead took up the fight against Gishin. To make things more difficult, if Takeru himself dies, the bomb inside Gaia will explode anyway.

Takeru awakens to his natural esper powers and gains control of six mysterious robots, being able to control them before even understanding where they come from. When these robots combine, they form God Mars, the strongest robot in the universe. From there, Takeru takes on a quest with his friends from the Crasher Squad to understand more about himself, his family, the six god robots, Zool, Gishin, and to save the Earth.

In the year 1999, humanity begins to advance beyond the solar system. The leader of the planet Gishin, Emperor Zule, aims to conquer the galaxy and ends up in a conflict with Earth as a result. In an act aimed to eliminate the Earth, he sends a baby named Mars to live among humanity. Mars is accompanied by Gaia, a giant robot that utilizes a new power source strong enough to destroy an entire planet. Once Mars grows up, he will destroy the Earth by activating the bomb within Gaia. However, upon arriving on Earth, Mars is adopted into a Japanese family and given the name Takeru. Seventeen years later, Takeru has grown a love for humanity and he refuses to detonate the bomb as ordered by Zule. However, the bomb within Gaia is set to explode if Takeru were ever to die, which would ultimately result in the Earth's destruction. 
Takeru possesses psychic powers (ESP) and decides to join the Earth defense forces and becomes a member of the Crasher Squad (an elite space defense force) where he and his friends take a stand against the Gishin attack. 
Unknown to the Gishin, five other robots were created in secrecy along side Gaia by Takeru's father and sent with Gaia to protect Takeru. The five other robots are Sphinx, Uranus, Titan, Shin and Ra. Whenever Earth is in danger, Takeru is able to summon the five other robots to combine with Gaia form the giant robot Godmars.

Marg was deprived his little brother, Mars, by Zure, and lost his parents. Therefore, he was living alone on the planet, Gishin. He became a member of guerrilla to riot against the dictator Zure, and he fell in love with Ruru, the daughter of the leader, Ura. However, the organization was destroyed. He was trapped by Zure, and he was brainwashed to become a soldier. Then, his long cherished wish that he would meet his brother again was realized… as a duel with him. 
(Source: AnimeNfo)

The movie is just a recap of the TV series. 
A.D. 1982, the planet alignment brought the human beings ordeal we should overcome, and it caused a convulsion on the Earth. During the conflict, a light fell on to the Myojinsho reef, and five lights scattered around the Earth as if they followed it. 
17 years had passed since then. A.D. 1999, human beings had developed all of the solar system, and began to embark for outer space. The Earth Defense Army organized an elite squad, Crasher, to provide for various happening in space. Myojin Takeru was the member of the team. He was found in the light fell on to the Myojinsho reef. Actually he was Mars who was born on the planet Gishin. When he grew up, he heard unearthly voice, 
“Mars, stop the Earthians’ advancement to the space. Explode the Earth” 
He was a living triggering device that had been sent by Emperor Zure, who plotted to conquer the universe. However, Mars, who had been raised as an Earthian, rejected the order, and made up his mind to face the severe fate. 
(Source: AnimeNfo)

Takeru Myoujin