_CAPSULE SUMMARY:_
Billy is teleported out of the Zeo Megazord, which is then taken over by Cog Changer himself. The Zeo Rangers use the Super Zeo Megazord against the evilly-controlled original-flavored Zeo Megazord, but Finster teleports Impursonator back from where Mondo tossed her, and she dumps the Rangers out of the Super Zeo Megazord, taking IT over herself! The Zeo & Super Zeo Megazords do battle, each controlled by a monster of the day of an opposing evil space alien faction. Auric the Conqueror is summoned to put a stop to this, but the left-wing hero tries to get the Megazords to talk things out instead of fighting, and ends up being knocked back to his Tiki form, never to be seen nor mentioned again! Impursonator screws up by exiting the Super Zeo Megazord briefly, and gets yanked back to the moon by Rita for a time-out.
Back at the Power Chamber, time is running out for Billy. Soon, he'll get so old he'll turn to nothing but a skeleton! The only hope is water from the Aquitian's Eternal Falls, which, like the Fountain of Youth, would turn him young again. Cestria, a female Aquitian who wore pinkish colored attire, and was implied to have known Billy from his time spent on Aquitar, teleported to Earth with the water. Due to the differences in physiology between humans & Aquitians, the effects of the water are merely temporary. In order to be fully restored to his true age, Billy will need to go to Aquitar for long-term treatment with the water of the Eternal Falls. He and Cestria teleport back to Aquitar, with Billy telling Jason to bid goodbye to the other Power Teens for him, since they are out of the PC at that time.
As for where our heroes were? Well, Cog Changer and his enhanced Cogs have begun to march through Angel Grove on a rampage. Impursonator is sent down to assist. So, the Zeo Rangers head off to stop them. Given the need for extra help in this situation, and the fact that the two teams are currently in contact with one another, the other three Aquitian Rangers teleport to Earth, and join Cestro & Delphine in action against the Cogs & pair of monsters. This marks the first time in PR history that two different teams of Power Rangers team-up in morphed combat. The Zeo & Alien Rangers defeat the Cogs & monsters together. But Cog Changer & Impursonator end up merging together and growing, into what could be called the "Cog Impursochanger". The Zeo Rangers use all of their Zords, now returned to their sole control, and destroy the combined threat.
A few days later, Billy contacts the Power Chamber, via transmission from Aquitar. Due to the stress of all the teleporting between worlds done of late, the transmission is really grainy and out of focus. But his message (which, of course, is done by a guy who sounds nothing like him) is clear enough: the Eternal Falls have cured him. Instead of returning home to Earth, he's decided to stay on Aquitar, having fallen in love with Cestria. The Power Teens wish him good luck, and most all will miss him. Billy would probably say something long, wordy, and profound, but David Yost was canned/quit after "King For A Day", so his extensive tenure on the show ends with a mere whimper of "bye".
As for Bulk & Skull during this two-parter, they spent most of it studying for, and taking, their detectives' exam. They fail, but because they continued taking it during a monster attack (believing it to be a ruse by Det. Stone to test their endurance under fire), they gain extra points and pass!