The weird genius of Headmasters is that it commits completely to a premise that shouldn't work: tiny alien robots piloting giant robot heads, and it actually makes you care about the mechanical logistics of it. The show doesn't apologize for how absurd this is; it builds entire plot threads around the Headmasters themselves as characters, not just gimmicks. You're watching 1987 toy commercial storytelling that somehow earns the strangeness instead of hiding from it.
Galvatron returns at the head of a fresh wave of Destrons, the Destron Headmasters, and sets out to wage war on Seibertron. The Cybertrons are saved when the Cybertron Headmasters arrive under the command of Fortress, who serves as the head of Fortress Maximus. Fortress reveals that he left Seibertron millions of years ago in search of energy and has at last made his way home. The Headmasters come from a planet called Master, where small robots built themselves full-sized Transformer bodies and became their heads by transforming. Now both factions field Headmasters, and they have entered the ongoing war. This mecha sci-fi adventure carries on directly from the third season of the original Transformers cartoon.