Cogs are the foot soldiers of the Machine Empire. The Machine Empire is ruled by King Mondo and Queen Machina. King Mondo and Queen Machine have a young son, Prince Sprocket. Also on staff are Klank & Orbus. King Mondo had found a galaxy full of resources for his Machine Empire. Although Lord Zedd and Rita Repulsa were there, King Mondo launched an attack on them at their moon palace. The cogs, in their Quadrafighters, attacked the palace on the moon. Lord Zedd and crew ran from the palace. The cogs did not make anything easier for Lord Zedd and his crew as they blasted them nearly every step of the way.
The Cogs had stopped their attack on Rita and Lord Zedd. This made King Mondo furious. The Cogs were sent off once more to attack Rita and Lord Zedd. The Cogs continued their attack, but Rita, Lord Zedd and the rest made it safely to Serpentera and left the galaxy. With Rita and Lord Zedd gone, King Mondo decided now was the time to conquer Earth and started with Angel Grove. The Cogs were sent down to begin the attack. The Cogs began their attack, but soon the Zeo Power Rangers arrived. The Cogs battled and were destroyed by the Power Rangers.
King Mondo had sent down numerous Cogs to infiltrate the secret location of the zords. King Mondo wanted the zords destroyed before the Rangers would use them. The Cogs arrived and began walking through the desert terrain. They soon spotted Bulk & Skull stranded on their patrol bike. At first they began to walk towards them, causing them to scream in terror. Once they surrounded them, one of the Cogs stated to leave them alone, as that was not their mission. The Cogs then walked toward some bushes and vanished from Bulk & Skull's sight. The Power Rangers soon arrived. The Cogs battled the Power Rangers. Some of them were destroyed. The rest retreated back to the Machine Empire.
Several Cogs were down in the junkyard, working on King Mondo's latest creation. Cog: Almost done. Our King will be so pleased. King Mondo had been watching Rocky and Jennifer and decided he wanted their computer program. King Mondo sent down several Cogs to attack Rocky and Adam, as they needed the password. As Rocky and Adam kept busy battling the Cogs, one Cog slipped away and took Rocky's backpack with him. The Cog then teleported to Angel Grove High School. As this was going on, several other Cogs on the Machine Skybase were dressed as doctors. They were modifying Orbus and then Klank according to King Mondo's instructions. The modifications will give Klank & Orbus the ability to make King Mondo's creations grow. Back at the high school, the Cog used the password to access the computer and then downloaded Rocky and Jennifer's program onto a disc. The Cog then teleported to the junk yard and placed the disc inside Silo. The Cog then teleported back to base. The Cogs battling Rocky & Adam eventually teleported away as well. Silo would later be destroyed by the Power Rangers.
King Mondo had used Boo Hoo the Clown to amplified Joey's cries. It had been a success and King Mondo wanted to increase the volume once more. Several Cogs and Boo Hoo the Clown were sent down to Angel Grove. The teens morphed. Some of the Cogs battled the Power Rangers. Alpha 5 had teleported down to protect Joey. The rest of the Cogs surrounded Alpha 5 and the baby carriage. Boo Hoo the Clown soon joined them. Boo Hoo the Clown electrocuted Alpha 5, shutting him down. The Cogs, Boo Hoo the Clown teleported out with Joey. They arrived at an electric plant, because King Mondo wanted to destroy the source of power for Angel Grove. The Rangers soon arrived. The Cogs battled the Rangers to keep them away from Joey. Klank & Orbus were there as well. Orbus made Boo Hoo the Clown giant size. The Rangers battled and destroyed Boo Hoo the Clown, and Joey's voice returned to normal.
Several Cogs were sent down to the battling cages. They work on modifying the pitching machine, which would turn it into the monster People Pitcher. People Pitcher would trapped the batter within, once a pitch was hit. When Bulk & Skull arrived, the Cogs teleported out, but their work was done. People Pitcher would later trapped Rocky within him. Plus the Cogs stole Rocky's Zeonizer. The four Rangers would soon arrive. The four Rangers pursue the Cogs, trying to get the Zeonizer back. Eventually they would. Red Ranger would enter People Pitcher and give Rocky his Zeonizer. The Rangers would then destroy People Pitcher.
Several Cogs were sent down with Digster to release the lava that was under Angel Grove. The Cogs worked hard under Digster's direction. More Cogs would arrive later, and they unknowingly lead Katherine to the cave, where the dig was continuing. Prince Sprocket, Klank & Orbus were also inside the cave. Katherine would be spotted trying to leave and several of the Cogs went after her. They eventually had her surrounded. Suddenly, Smokey, a dog Katherine had trained, arrived. All of the Cogs, except one, ran up a tree, frighten of Smokey. Katherine would knock out the remaining Cog. King Mondo would call off the search for Katherine, as he was upset at the Cogs. The Cogs went back to digging up the lava. Later, the Rangers would destroy Digster and prevent the lava from reaching Angel Grove.
Ernie was hosting the Captain Pete and Puppet Man show at his Youth Center. The place was filled with kids. This had given King Mondo the idea to use the kids as their evil drones. Klank had made a transmitter. Several Cogs were sent down to the show to plant the transmitter on Puppetman. The kids were not frighten, as they thought the Cogs were part of the show. One Cog eventually planted the device on the belt of Puppetman. Puppetman would turn evil and use his beam to turn the children evil as well. Later, the Rangers would destroy the transmitter, Alpha 5 would rebuild Puppetman, and the children would return to normal.
Prince Sprocket had wanted to make a movie of his own. After watching a movie set, Prince Sprocket wanted the monster costumes from the set. Cogs were sent to get the costumes. Two of the Cogs were mistaken for monsters for the movie and they were dragged to the set. When the movie star, Biff Starr, made to attack them, he was very hurt. Rocky, who had become his last minute side kick in the movie, stopped the Cogs from hurting Biff Starr further. There was a commotion as several Cogs had stolen monster costumes and were running away. Tanya, Rocky, and Katherine chased after the Cogs. They soon came into a field which had numerous Cogs there. Adam and Tommy had joined them. The five teens morphed. The Cogs battled and were defeated by the Power Rangers. Later, Video Vulture would captured the Rangers and put them in Prince Sprocket's movie dimension. There were more Cogs working on the sound equipment for the movie. Eventually the Rangers would learn if they change the ending of the movie, they could break free of the dimension, which they did so.
King Mondo and Queen Machina had not been happy to see a space ship land in Angel Grove without their permission. The space ship had been carrying Cestro, who had come searching for Billy. Close on Cestro's heels, was Hydro Contaminator. At first King Mondo and Queen Machina was not happy to see distress on Earth that was not cause by them, but they soon decided to take advantage of it. King Mondo and Queen Machina sent down several Cogs to help Hydro Contaminator battle the Power Rangers. The Cogs battled the Rangers and let Hydro Contaminator get to the lake to contaminate it. The Cogs would be defeated by the Power Rangers. Several more Cogs landed with Prince Sprocket into the water treatment plant. Hydro Contaminator had gone there to find more water. Prince Sprocket promised Hydro Contaminator all the water he wanted, if he destroyed the Rangers. The Cogs and Prince Sprocket watched as Hydro Contaminator battled the Rangers. Eventually the Rangers would destroy Hydro Contaminator.
King Mondo had been watching the Junior Botanical society. Rocky had created a hybrid and the plant like to eat metal. When Rocky walked away, Skull took a clipping of the plant and planted it. The plants had given King Mondo an idea. Prince Sprocket and several Cogs went to the Junior Botanical Greenhouse. A couple of Cogs entered, while the rest stood on top of the roof with Prince Sprocket. Soon Adam and Rocky came walking up towards the greenhouse. Prince Sprocket: Oh Power Peasants, over here! Nice weather, isn't it? Rocky and Adam morphed. The Cogs battled the two Rangers as the other Cogs left with both Rocky's and Skull's plants. The two Rangers tried to stop them, but they couldn't. King Mondo would create two monsters from these plants. Pollenator, one of the monsters, would later be destroyed by the Power Rangers.
Three Cogs were walking along the building wall of Angel Grove High School. They had been sent down to capture the mysterious piano player (Skull) for a birthday present for Queen Machina. The Cogs stood outside the music room's window for a moment and one of them confirm it was the piano player they were looking for. The Cogs had some difficulty climbing into the window, but they managed to get through. The piano player, wearing a clock, was leaving in a hurry. Adam had just entered the room when the Cogs did. The Cogs and Adam stare at each other. The Cogs then teleported out. King Mondo was furious at them for their failure. The following day, the Cogs were sent once more back to the high school. The piano player was back and the Cogs were out to capture him. Instead the Cogs ran into trouble with Tommy, Katherine, and Adam. The Cogs battled the three teens, but were soon defeated. King Mondo then created Fortissimodo. More Cogs arrived with Fortissimodo. The Cogs and Fortissimodo were successful in capturing the piano player, but it only lasted a moment. Green Ranger was leaping towards them. Soon the rest of the Rangers arrived as well. The piano player escape and Fortissimodo was destroyed by the Power Rangers.
Several Cogs were sent down to Angel Grove to keep the Power Rangers busy as Mean Screen planted a virus in the computer system. This caused much chaos, but eventually the Power Rangers would destroy the virus and Mean Screen.
The Machine Empire had been successful in firing at Billy's space pod and knocking it off course. The Power Rangers were trying to help Billy by going to a warehouse and getting fuel cells. Several Cogs, Klank, Orbus, and Mechanizer arrived and tried to stop the Rangers. The Cogs were unsuccessful in stopping the Rangers, and Billy was able to return to Angel Grove safely.
The Machine Empire had sent down Robo Cupid to make humans fall in love with their machines, and that way they would not cause his soldiers any harm. King Mondo and Queen Machina were aware that three of the Rangers, (Billy, Tommy, and Katherine) were at the ski slopes. King Mondo wanted to keep the Rangers at half strength. Several Cogs were sent up to the ski area. The Cogs made their way through the crowds with no problem, as people thought they were the Norwegian Ski team. The Cogs went to the run "Widowmaker". The Cogs removed the warning signs placed there. Katherine was right behind them. The Cogs battled Pink Ranger, and were destroyed by her. Unfortunately Katherine could not find the warning signs. Tommy, Billy, and Heather had been snowboarding on the Widowmaker, and Heather went over the cliff. Heather managed to grab the edge of the cliff before she went completely over.