True to name, the Transformers franchise has had several different forms and variations, with one of the most well-known takes on the robots in disguise being Beast Wars. This era replaced modern vehicles with animal alternate modes, introducing a whole generation of bestial bots. This wasn't the franchise's first foray into such disguises, however, with the first line of beast "Transformers" being largely forgotten.
The U.S. toyline Battle Beasts was a failed '80s franchise, but its release in Japan firmly connected it to the Japan-exclusive Transformers anime. This would see it gain a bit more traction in the land of the rising sun, and eventually, an anime/manga reboot would be developed. Here's the overlooked story behind Beastformers and the Transformers' original Beast Era.
Rise of the Beastformers
The Beastformers' toys were developed by Takara in 1986, and the company still owns the rights to the property. Takara, now Takara-Tomy, handled and still handles Transformers in Japan, with Hasbro being the company's equivalent in America. Takara had Hasbro localize the franchise outside of Japan, though there was one notable difference. While the very name Beastformers (also spelled BeastFormers) made it clear that the line was in some way connected to Transformers, Hasbro instead localized the property as Battle Beasts, which had no such ties to the robots in disguise. This was likely due to Transformers then being in the first of its waning years in America.
Japan, on the other hand, would still have several years worth of exclusive Transformers anime and manga until the "mecha" anime franchise would begin to lose steam, and these served as the media face of the Beastformers. An episode of the anime Transformers: The Headmasters prominently featured the Beastformers while also further explaining to audiences their story and connection to the Cybertronian conflict.
The world of the Beastformers was called Planet Beast, which was full of anthropomorphic animals. Eventually, the Decepticons invaded, with Galvatron giving weapons and technology to the evil Alligatron, a humanoid alligator. A faction of heroic Beastformers are likewise given weapons by the Autobots, with their leader White Leo running a group of mostly mammalian "Autobot" Beastformers against Alligatron's reptilian "Decepticon" Beastformers.
Though they had the name Beastformer, the characters and their toyline of figures could not transform -- though they did retain the Transformers' faction sigils. The toys also had a "rock, paper, scissors" motif representing fire, wood or water, with these strengths and weaknesses used for a role-playing aspect. The figures also came with melee and long-range weapons, with the well-armed menagerie being far deadlier than any mere Calico Critters.
Battle Beasts and the Beast Saga
The American equivalent, Battle Beasts, wouldn't make much of a splash as far as '80s media franchises went, and despite the connection to Takara's premiere franchise, Beastformers didn't fare that much better. This would see the intellectual property languish in obscurity, with neither side of the pond acknowledging the armored animals for quite a while.
Takara-Tomy would finally break this trend in the early 2010s, introducing the multimedia franchise Beast Saga. This soft reboot of the Beastformers concept would take the form of a five-volume manga from Saikyo Jump, a game on the Nintendo 3DS and an anime that had over 50 episodes (though several of these were unaired). This short-lived version of the franchise wouldn't have any connection to Transformers, however. There would also be an American Battle Beasts comic book from IDW, though this didn't last long, either.
Despite how obscure it's remained, the Beastformers franchise was in many ways prophetic of the forms that the Transformers line would take. The Beastformers themselves heavily resembled the organic armored Pretender shells that Transformers wore in the year or so after the Beastformers were introduced. The idea of Transformers having an organic outer shell to disguise themselves would become even more prominent by the time of Beast Wars, where animal robots waged war on an alien world. A Japanese entry in the Beast Era even introduced Lio Convoy/Leo Prime, who transformed into a white lion. Thus, while it never had much success itself, the Beastformers line was instrumental to the entry that would save Transformers in the '90s.