Disclaimer: Knowing full well there is a wealth of resources available to fans of the "Justice League" animated series, I have no intention of doing a bunch of dry story synopsis with the occasional new screen grab. I will chronicle, within reason, J'Onn J'Onzz's specific journey over the course of the series, but chiefly I will be reviewing the episodes through my own jaundiced perceptions.
One of my only objections to Stan Berkowitz's script was that it was Superman who suspected something underhanded about the goings on, and initiated an investigation. It seems painfully out of character for J'Onn to play Watson to Superman's Holmes.
Donning spacesuits on a nearby moon, Superman asks if J'Onzz sees anything wrong. "Where do I start? The loss of life-- the echoes of our own pasts." While this distraction seems in keeping with J'Onzz's history, it still seems off that it was the Man of Steel who deduced that the planet Stewart was accused of destroying must still exist, because that world's moon was still intact in its prior orbit. At least it was the Martian who discovered the machinery which facilitated the illusion. "When I was a child on Mars, we had small toys called 'illusiotrons.' They could project crude images over objects, and even empty space... The engineering principles appear to be the same... It would explain why this moon's orbit has remained intact." The pair were then attacked by a ship piloted by classic League villain Kanjar Ro, who was defeated and forced to reveal his role in the Manhunter plot against the Green Lantern Corps.
With Stewart cleared of charges, the Manhunter Cult launched an assault on the Corps base of operations, Oa, and their masters, the Guardians of the Universe. The League and a rinky half-dozen standing Corpsmen took on the Manhunters. J'Onn J'Onzz wasn't very visible, as the spotlight understandably gravitated toward Stewart. However, he had an impactful moment drawing fire intangibly, then passing into an Oan citadel, where a Manhunter had taken control of the planets defenses. The Martian wraith moved intangibly through a control panel, reached his hand into the Manhunter's brainpan, and ripped his cybernetic mind out with brutal efficiency. Stewart proved himself the greatest of the piddly Corpsman present in assuring victory over the Manhunters. As Stewart dismissed his fellows for assuming his guilt before trial, he walked up to J'Onn J'Onzz and company, who asked if he was all right. "You believed in me, even when I didn't believe in myself... Let's go home."
It was nice when there were hints of the comic book Stewart in the cartoon. While the actual plot was lifted directly from a Hal Jordan story from the 70's (as were elements of the episodes that immediately preceded and followed,) Stewart's being accused of the inadvertent destruction of a planet echoed the same occurrence, with Stewart more genuinely at fault, in the 80's series "Cosmic Odyssey." Beyond a self-destructive guilt though, the two interpretations remained vastly different at this juncture. The resigned, thoughtful GL who rocked a classic 'fro couldn't have been more different from the gruff animated soldier, in a different uniform with a hi-top fade.