The Battle Story is a narrative portrayed solely with released Zoids models. Specifically, Zoid Boxes and promotional media included in model kits have had a "Battle Story" attached to them. Not all model kits have a Battle Story included with them (notably, international releases had plain boxes without any battle story printed on them)
Original Battle Story
Beginning fairly early after the start of the original Japanese Zoid releases, the battle story first introduced the conflict between two rival nations: the Helic Republic and Zenebas Empire. Their main weapons were Zoids, living war machines built from metal-based lifeforms native to planet Zi. The Zenebas Zoids were mostly red and silver and more armored, the Helic more skeletal and favoring blue and grey.
The line expanded and drew in fans, and was thus given a proper ongoing story, with the creators wanting to appeal to fans of science fiction and animation. The two nations' conflict turned into an ongoing series of stories included on the boxes and published in various magazines and books. History of Zoids, published in 1985, covered Zi's history as a planet wracked by natural disasters and conflict, King Helic's uniting the original tribes and formation of the Republic, the Empire's bitter splitting off after his son Helic II took over and the younger Zenebas was betrayed by the era's politicians, and much of the earlier battles in the resulting war over territory on the Central Continent. As more advanced model kits were added to the line, a human element was added to the story: mainly, a ship from Earth (the Globally 3) crashlanding on Zi. Earth technology made its way to both sides, accelerating the arms race and making for many stronger Zoids.
In 1986, the Ultrasaurus was released, and billed in-story as the machine that would defeat the Empire. It nearly succeeded, but Zenebas and his forces fled to the Dark Continent Nyx, soon returning with new-model Zoids like the Death Saurer. The Republic was driven back and forced to hold the Empire off with guerrilla warfare in the mountains, paving the way for the brief 1/24 scale line (notable for featuring the Battle Rover as the winner of a fan design contest. The Republic's counterattack came in the form of the Mad Thunder, and as Zenebas again turned to the Dark Continent for help, he was betrayed by Guylos, whose new "Dark Army" Zoids attacked and absorbed the Empire Army.
1989 thus marked a drastic change in the line's focus, the first catalogue even calling it "Zoids New Century" (a title unrelated to the anime series Zoids New Century /Zero). The more ambiguous conflict became more "good versus evil", with Guylos described as having a "merciless, cruel fighting style [...] beyond imagination" in Tomy's material, and Shogakukan's version of the battle story abandoning telling things from both sides to give only the viewpoint of a Republic soldier portrayed as a hero. There were no windup kits released after the Cannonfort in April of 1989, the toys instead focusing on "Gradeups", curvy techno-organic designs with vacuum metalized parts, build-it-yourself motor boxes, and interchangeable custom parts.
The line ended in the late months of 1990, King Gojulas and Descat marking the final designs. Battle story Zi came down to a final showdown between the nigh-unstoppable King Gojulas and various Dark Army Zoids (including Gilvader), only to have the conflict cut short as a comet struck Zi's third moon, raining down meteor destruction and leaving the entire planet in disarray.
While the old battle story and the 1999 revival left nearly thirty years post meteor disaster undetailed, Tomy's Rebirth Century revival (2008-present) picks up where the old story left off. After retelling the final battle with King Gojulas, it moves on to a Zi torn by magnetic storms and faction tensions, using it as a reason to rerelease both old kits (Gilvader and King Gojulas included) and new designs.
New Battle Story
The Zoids revival in 1999 included both an anime and a new battle story. After decades of peace, the current Emperor died, leaving only the young Rudolph as his heir. His regent, Prozen, took the opportunity to resume the conflict between the Guylos Empire and the Republic. Early on, both sides used their past Zoids, the model line focusing entirely on reissues of popular past kits.
As technology advanced, entirely new designs were produced, the first being the Rev Raptor and Geno Saurer. Many of them were also tie ins to the Chaotic Century anime, including special pilot figures of characters who used them while the Zoids did different things in the Battle Story. The accelerating arms race came to a head with the Death Stinger, which proved an uncontrollable berserker and only served to further the Guylos Empire's gradual loss.
Their retreat to the Dark Continent was not as it seemed, and in 2004 (four years after the first anime series finished its run), Prozen was revealed to be Zenebas' son...and the current ruler of the Republic his daughter under the alias Louise Elena Camford. The entire war until now had been a ruse to weaken both nations, and in a bitter coup ending with his own death Prozen engineered the rise of Neo Zenebas. His son took over the reins, driving the Republic forces back to the Eastern Continent.
The toyline shifted to match, introducing the new posable "Blox" kits (first sold in 2002) as the creation of humans who had fled there to remain neutral in the original conflict. They sold their work to both sides during the Republic's bid to regain their homeland. The ensuing battles—and the battle story portion of the toyline—ended with the Republic reclaiming their capital, forcing the Zenebas Empire back to the western half of the Central Continent.
Main article: Three Tigers (Battle Story)
Released in 2004, the Three Tigers line consisted of six kits: three legendary Tiger-type Zoids (one formed via a combination of two separate kits) and the Dekalt Dragon (also a combination).