Gunarcleans are actually greys'. But they're mostly green (can be grey). They're the most dangerous species because of their fast reproductive period. They take over many planets to keep the species alive.
Their first act of making room for their species is artificial islands. Next was moving all animals to another continent. This killed many organisms and unbalanced the ecosystem. Then, They colonized their moon as well as making another one. Finally, they took over planets. On Gunar, they found ways to control pollution. One way is huge dams. Another is shooting a huge rocket into space that was full of waste. They even have machines that filter out wastes in the atmosphere.
Gunarcleans have two main enemies. The first is the Roshak. Roshaks are just trying to eliminate the threats of Gunarcleans. The more interesting one is the Geral. Gunarcleans took over Gerale. A small fleet of Geral ships went searching for refuge and found another planet.