Normally, Gleek is the sentient pet of Zan and Jayna, The Wonder Twins, though their presumably evil counterparts are nowhere to be seen. While the regular series Gleek is a well-meaning incompetent but brave sort, Evil Gleek is far sharper, cunning but cowardly when confronted. Even without the Twins on hand, Gleek is the mascot of the vicious Super Enemies. Appearance-wise, his eyes are shaped like those of a cat, with his ears, teeth, paws and tail all elongated from those of the regular Gleek. Main-Universe Gleek did not appear in the episode, making him the only 'good universe' counterpart not to do so.
When Superman arrives into his evil counterpart's dimension, at first he attempts to fake being his counterpart, till his ruse is exposed and the Enemies begin to chase him. With the aid of a scientist native to this other Earth, Superman manages to get hold of some contained anti-matter, hoping to trigger his return to the reality of the Super Friends.With the Super Enemies still in pursuit, Evil Gleek tries to stop Superman and imprison him. He grabs the anti-matter with his tail and leaves, grinning all the while. Superman, blasting at the ground by Gleek with his heat vision, sends the wicked mascot scampering off in fear. He later uses the anti-matter at Mount Vesuvius and manages to leave. Presumably, Evil Gleek saw Superman one last time when he fulfilled his promise to the helpful scientist and returned with the Super Friends to stop the Super Enemies.