Quatros was once a planet where Hero Factory continuously mined for the rare Quaza stones. Akiyama Makuro would use this precious jewel to power his Heroes in the Assembly Tower. From what we can gather, there aren't many planets that have this stone and the few that do are well protected, as stated in Comic 6: Savage Planet. Apparently, taking away the Quaza from Quatros was causing the planet to undergo unusual changes in its vegetation and animal life. It is also stated in the comic that the planet would be destroyed completely if HF continued to mine there.
Once the scientists at Hero Factory realized this, Quatros was put under quarantine and, as stated in the comic, had a protective forcefield placed around the hemisphere. Aldous Witch, who has envied the power that the Quaza stone can give heroes, has decided to take root in Quatros and continue mining there despite the consequences. Witch has even taken advantage of the unusual effects that Quaza has on the planet. With the stone's power he has gained several minions mutated by the stone and seems to have some control over the plant life on Quatros. Currently, he has trapped Stormer and his team on the dying planet.