Beastmen
The Beastmen Empire is made up of Lord Genome, his Supreme Generals and countless number of Beastmen. The Generals command a personal Gunmen and a fortress-type Gunmen, each with an army of Gunmen that are based on the characteristics of the general (e.g. flight-type, aquatic-type, etc.) Gunmen used by the Beastmen run on solar-powered batteries, because Beastmen lack the Spiral Energy normally used to pilot Gunmen. As a result, they are useless at night.
The personal Gunmen in the Beastmen Empire, piloted by the Generals and high ranked militants like Viral, all have two faces, usually one on the chest and one on the head (Likely a reference to the Gunmen of the original Spiral Warriors, who all had two faces in a Gurren-Lagann style setup).
Read more about this topic: List Of Gurren Lagann Mecha