Over the course of a war that consumed Green Gate, the tides began to turn against Cosmo's species as countless of their kind died, either by the hands of the enemy or from using Mover Mode to combat the enemy. Understanding that they would perish one way or another if they stayed on their home, the planet's leader Earthia decreed that they would have to leave Green Gate to survive and find a new home. Refusing to run and hide, Lucas stole the Planet Egg of Green Gate and mutated himself and his followers with it to give themselves more power to combat the enemy, causing Green Gate to slowly wither away, which Earthia soon noticed. Devastated at what Lucas and the others had become, Eathia and the females abandoned their world and their mutated comrades to destruction by their enemies.
As Lucas and hundred of other males continued to fight the enemy on Green Gate, Earthia had their world bombed with nuclear weapons to stop Lucas and the others before they could endanger the universe. However, five males, including Lucas, survived the onslaught. These five were to become Dark Oak and his henchmen through a finishing phase of their evolution and became the leaders of the Metarex.
In the episode, "Eye Spy", Sonic and his friends visited the desolated Green Gate and found its ruined capital city where they came across a holographic message from Earthia retelling the events that happened on the planet.