Cog Changer was the last monster created by the Machine Empire. Sent by King Mondo to battle the Zeo Rangers, Cog Changer used his special, machine-controlling cogs to crash the Zeo Jet Cycles, then to make the Cogs super-strong. When the Rangers summoned the Zords to battle Rita's Impursonator, Cog Changer was able to shoot one of his cogs into the Zeo MegaZord. After the fight was over, the cog caused the Zeo MegaZord to go AWOL, trashing the innards of the Zord Holding Bay, and shooting off into the countryside. It was here that Cog Changer leapt into the Zord's cockpit and assumed total control of it. When Impursonator gained control of the Super Zeo MegaZord, the two monsters used the MegaZords to fight throughout Angel Grove, destroying much of the city. Cog Changer was finally expelled from the Zeo MegaZord when Tanya destroyed his cog and Katherine attacked him inside the MegaZord's cockpit. Cog Changer soon returned with a battalion of Cogs, attacking the Angel Grove Colosseum. He apparently put his differences with Impursonator aside, and teamed up with the pink creature to defeat the Zeo and Aquitian Rangers. Upon growing, Cog Changer had the daylights beaten out of him by the Super Zeo Zords. At the command of King Mondo, Cog Changer combined with Impursonator to form a super monster. But even this wasn't enough, and Cog Changer was destroyed by the Warrior Wheel.