God Mars

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.

GoShogun

A meteor strikes the Earth and is found to emanate a powerful new energy called Beamler, which is used to power a battle robot, GoShogun, and a teleporting fortress, Good Thunder. The Docougar Crime Syndicate, lead by crime lord Neo Neros, try to steal the secret of the energy from the inventor of GoShogun, but he kills himself rather than let them acquire it. His son is targeted by Neo Neros next, but he is taken in by the crew aboard Good Thunder, who travel the world fighting NeoNeros's forces with GoShogun. (Source: Wikipedia)

Golden Warrior Gold Lightan

When a young boy called Hiro finds what appears to be a broken lighter in an empty field, it changes his life forever. This lighter is actually the Gold Lightan, a robot that fell to Earth from the Robot Dimension. When called upon to defend the Earth from Ivalda the Great's evil robots, Gold Lightan transforms into a giant super robot, known as the Golden Warrior. Gold Lightan joins forces with Hiro's and his gang, the One Pack Rangers to protect the Earth from the evil schemes of Ivalda the Great and his armored forces.

Space Knight Tekkaman

Tekkaman is just an average bright boy in his everyday life. However, modern science can turn him into a mighty space warrior. This becomes a reality when aggressive aliens come from space to invade our planet. Armed with a space lance, Tekkaman gallantly goes into action against the grotesque space creatures. During his battles he encounters a mysterious young man from another planet who helps him out whenever he is in danger. (Source: Absoluteanime)

Tetsujin 28 FX

Decades have passed since Shotaro Kaneda and Tetsujin 28 protected the world but evil continues to strike! It’s time for a new hero and a new robot, Tetsujin 28 FX, to protect the world! Masato Kaneda returns after mysterious vanishing a year ago to take up the reins of protecting the Earth along with his family and friends from the diabolical Neo Black Gang. With upgrades for Tetsujin 28 FX from Masato’s brilliant mother Yoko, along with Shotaro and the original Tetsujin 28 occasionally leaping in to help, can they stop the Neo Black Gang and all the other villains and rogue robots?! (Source: Discotek)