Yatterwan began as an unfinished prototype rescue robot, designed by Gan Takada's father and later completed by Gan. This dog-shaped mecha incorporates functional elements typical of emergency vehicles: a siren, bell, and dual fire hoses mounted on its back. Offensively, it launches iron pellets from its nostrils. A bone-shaped power source named "Mecha-Tonic" fuels Yatterwan, triggering sudden bursts of strength to withstand powerful attacks. Its signature combat function involves deploying numerous miniature robots from its mouth; these land animal-shaped units combine their weapons to destroy enemy mecha, consistently resulting in explosions that form skull-shaped smoke clouds, a recurring tactical resolution.

Destroyed in battle during the original series, its damaged remains were reconstructed into the significantly larger and more advanced Yatter-King. This new form resembles a hybrid between a fire engine and a dachshund, incorporating enhanced offensive systems: a tail functioning as a firehose, a rear projectile launcher, and a carrier body capable of transporting smaller robots. The 2008 series adaptation reimagined Yatter-King's origin, depicting it as a combination of Yatterwan with a newly introduced, combat-oriented mecha named Yatter-Zero, which contributed a regal aesthetic.

Specialized mecha iterations were developed for specific environments. Yatter-Pelican, an airborne unit introduced in the original series' 14th episode, releases bird-shaped mini-robots and consumes fish-shaped Mecha-Tonic for power amplification. This version exhibited a boastful personality, with the 2008 adaptation adding sporadic English phrases to its speech. Yatter-Angler, appearing in the 27th episode, serves as an all-terrain and submarine-capable unit equipped with an underwater cockpit. It utilizes fish roe-shaped Mecha-Tonic and deploys marine creature-themed mini-robots, featuring vocal effects simulating submerged communication.

Within expanded media, Yatterwan's legacy continued through robotic soldiers modeled after the original Yatterman duo in "Yatterman Night". These mass-produced units replaced the traditional Kendama and Electric Stick weapons with laser pistols. The character also transitioned to a live-action adaptation, maintaining its recognizable mechanical canine form. Beyond screen appearances, a physical monument honoring Yatterwan exists at Minamitama Station's north exit in Inagi City, Tokyo, created as part of mechanical designer Kunio Okawara's project.