It was made as competition to rival toy company Takara's Brave Series, which was also being animated by Sunrise. It has many differences from it however. Its main feature was casting elementary school children as the protagonists of each show, with the ancient warrior of light, Eldran, making the robots only usable by children from each of these series when he himself could not directly face the main enemies of the season directly. With these robots, they take on any of the various threats to Earth that exist. From show to show, Eldran's involvement increases greatly.
All of the series in the main trilogy are connected to each other, separated by about 1 year each and taking place in different cities.
- Absolutely Invincible Raijin-Oh (1991)
- Energetic Explosion Ganbaruger (1992)
- Hot-Blooded Strongest Go-Saurer (1993)
There was a fourth one to be made, Perfect Victory Daiteioh, but it was instead made into an OVA pilot episode and a manga based on it for the 10-year anniversary celebration of Eldran. It appears in Super Robot Wars NEO, however.
The typical mecha in an Eldran show involves a trio of smaller robots piloted by three people at first, who have the ability to combine into the titular robot of the series. Then, as the series goes on, there's a new transforming mecha or two that are of a similar size to the main robot, and have the ability to combine with said robot in a Super Combination. None of the mecha in this series are sentient, as they're either piloted or remote-controlled. The units also tend to involve animals of one kind or the other.
Additionally, the main Eldran robots all have large wings due to the single flying component of the combination, and use swords and shields as their main weapons. The auxiliary robot(s) tend to provide additional firepower with large cannons (Revolger and Magna Saurer), or can finish more powerful enemies on their own (as is the case with Gekiryuger and Gran Saurer). Nearly all of the main mecha's finishing moves involve immobilizing the enemy using their shields (with the possible exception of Go-Saurer) before the final slash. The Super Combinations however don't use shields, but still immobilize the enemies before the final attack.
- The mecha types are similar to the ones used in certain Super Sentai series, where the main team acquires a transforming mecha in addition to their own combining mecha that is about the same size and can further combine with the main robot.
- The only characters other than Eldran to appear in all three TV series include General Takeda of the Defense Force and the newscaster Etsuko Ōmiya.