Despite its name, Mecha-King Ghidorah is not a fully mechanical robot but a cyborg; it was built in the year 2204 around the comatose body of King Ghidorah after he was defeated by Godzilla in 1992. Mecha-King Ghidorah was sent back to 1992 to battle Godzilla in Tokyo before he could destroy Japan, and succeeded in halting his rampage and dumping him in the ocean, though it was destroyed in the battle. In Godzilla vs. Mechagodzilla II, the remains of Mecha-King Ghidorah were salvaged by G-Force, who used its components to build Mechagodzilla.
Mecha King Ghidorah played Mecha Hydreigon in Tyranitar vs Hydreigon (1991)
He's a giant pokémon