Greenman vs. Gyaron (グリーンマン対ギャロン, Gurīnman tai Gyaron?) is the fifteenth episode of Go! Greenman.
Tonchiki, attempting to impress his master, presents Maoh with Gyaron who is mutated from a nearby minion. Tonchiki explains to Maoh that Gyaron is capable of conducting electricity from his large head. Foolishly, Maoh touches Gyaron's head and is shocked with a powerful burst of electricity. Despite quite literally being shocked, Maoh approves of the creation. Above ground, a small group of children are playing baseball. However, the pitcher throws it too far to the left and it rolls down a hill into some brush. One of the boys chases after it, but right before the boy's eyes, the ball transforms into a Minion of Maoh who then further mutates into Gyaron. Gyaron chases after the boy but the other two children use their Green Calls. Greenman appears out of thin air directly in front of Gyaron. The two run towards each and begin fighting. Gyaron is quickly swept off his feet and beaten on multiple times. Realizing Gyaron was near defeat, Maoh orders Tonchiki to make Gyaron grow. Greenman also alters his size and they continue fighting. Gyaron is thrown around just like before, and decides to use his electricity. Just as Greenman is about to hit Gyaron's head with a powerful blow, he is overcome by electricity. Weakened, Greenman is further beaten with ease. He summons the Greenman Stick, and with it effortlessly prevails. Ironically, Gyaron is defeated with the Flash Shock attack.