If you're looking for anime similar to Genki Bakuhatsu Ganbaruger: Hyakka, you might like these titles.
When the legendary Guardian Eldoran is badly wounded by the fifth-dimensional invaders of the Jaku Empire, he has no choice but to leave the Earth's only salvation - the mighty robot Raijin-Oh - in the hands of the first people he can find ... which happens to be a classroom of 5th Graders. The children reluctantly take up the responsibility, only to find that the Jaku monsters invading their planet have become the living incarnations of the things they dislike the most! Can the Earth Defense Class successfully learn to work as a team, overcome their stigmas and defeat the forces of evil while (futilely) attempting to teach Jin how to perform decimal division?
The Kikaika Empire invades our solar system, and in a matter of moments they take over and convert Neptune, Uranus, Saturn, Jupiter,and Mars, and set their sights on Earth. However, one thing stands in their way. Earth's ancient protector and soldier of light, Eldoran. To fight this menace he gifts a 5th-grade class with 3 huge robotic dinosaurs, with the power to merge and form the giant robot Gosaurer, which they then can pilot and use to stop the Kikaika Empire's advances.
When an alien force attacks Earth, a giant sword falls onto the campus of Paradise Elementary School, transforming it into a flying vessel. The fate of the planet lies with one group of kids who must pilot powerful mecha to stop the invaders, before it's too late!
A ship crewed by earthlings crashes on Chronos. Believing themselves stranded, the crew volunteers to fight along the Machine Robos.
Two years have passed since the legendary force Build Divers battled the second Coalition of Volunteers to save the EL-Diver. Gunpla Battle Nexus Online (GBN), where these events took place, has been upgraded to provide sensory feedback for more realistic play. But as GBN becomes even more exciting, there are Divers who play with their own motivations in mind. Hiroto is a Diver who wanders alone through the Dimension, playing as a mercenary. Kazami is a frivolous, independent Diver who joins one party after another, pursuing the one he admires. May is a solo Diver surrounded by an aura of mystery, who plays Gunpla Battle night and day. And Parviz is a lonely novice Diver who is interested in team play, but out of shyness, he has never managed to seize the opportunity. Each of them is alone, but the course of events will end up uniting them into a new team of Build Divers. What awaits Hiroto and the others is a boundless super-experience that far transcends GBN.