Zoids are beast-like fighting machines used in both everyday use such as transportation, and special use such as war. Some types of Zoids, know as Organoids, are miniature Zoids that are living organisms. These Organoids have the capability to fuse with a non-living Zoid and make it much more powerful.

Van (Ban) Freiheit discovers a Zoid Organoid in an abandoned laboratory while running from two strangers piloting Zoids. Also in the laboratory, in an animated suspension tube is a strange girl. He breaks the tube open and takes her and the Organoid with him. Spotting a ruined Shield Liger Zoid outside nearby, the Organoid fuses with it and repairs the damages. Making his escape, Van names the Organoid Zeke, and decides to keep him as a friend. The girl, who says her name is Fiona, wants to find something called Zoids Eve, and so Van, Zeke, and Fiona begin their adventure.

[Source: AniDB]

Zoids—powerful animal-shaped combat mechs—are no longer used in warfare, but in organized sporting competitions. The Blitz Team, a group of pilots struggling to carve out a niche for themselves in the Zoid battling leagues, experience a stroke of luck when Bit Cloud, a vagrant junk dealer, wanders into their midst and proves himself capable of piloting the temperamental Liger Zero, a Zoid that refuses to let anyone else into its cockpit. Led by Bit and the Liger, the Blitz Team steadily make their way to the top—but along the way they attract the unwelcome attention of the Backdraft Group, an organization of Zoid pilots that operates outside the laws set down by the Zoid Battle Commission. The Backdraft want powerful Zoids to add to their ranks, and they have their eye on the Liger Zero...

R.D. is a delivery boy who works for a company called Mach Storm in order to earn money to search for the legendary Alpha Zoid. A Zoid that he heard rumours about from his dad that he passionately believes in. Mach Storm also doubles as a Zoid Battling team. In R.D.'s first Coliseum Zoid Battle, he encounters a team that can fuse Zoids. R.D. soon discovers that he has a Zoid that can computably fuse with his Zoid, Liger Zero. After this happens R.D.'s adventure to discover the truth about the Alpha Zoid begins.

[Source: Anime News Network]

Natural disasters have devastated planet Zi, killing off almost all life. A thousand years later humans have gradually re-established civilization, salvaging ancient Zoids through diving and mining efforts. In a village whose most previous item is a giant sword which they worship as a holy symbol. A teenage boy discovers an ancient Liger-type Zoid while on a deep water salvage operation. Suddenly the village is attacked by skeletal Bio-Zoids intent on stealing a powerful generator located in the village. Our teenage hero awakens the Liger and discovers that the town's sacred sword is the Liger's weapon, together they fight off the mysterious Bio-Zoids. At least for now...

[Source: AniDB]

A quest for freedom and legendary treasure begins when a cheerful, young adventurer follows his father's footsteps to become the greatest Zoids hunter.

[Source: Netflix]