Ben Tennyson (Classic)/OV flashbacks

In A Jolt from the Past, Ben as Stinkfly fought a Megawhatt. After reverting, he grabs a Mr. Smoothy cup and traps the Megawhatt in it. Thinking that he has won, the Megawhatt escapes the cup and duplicates. Ben remembers he has Feedback and turns into him. He sucks the energy out of the Megawhatts, which make them go to sleep.

In Trouble Helix, the Tennysons meet Malware, an incomplete Galvanic Mechamorph accidentally created by Azmuth, who loses his patience and kidnaps Albedo, Azmuth's assistant to complete himself. Eventually, he is turned into a more powerful form but he is defeated by Diamondhead.

In The More Things Change: Part 1, Ben as Four Arms fought Malware. While at first it appeared that Ben was winning, Malware managed to grab the Omnitrix and forced Ben to revert to human. Malware confronted Ben and taunted him about his defeat, which allowed just enough time for the Omnitrix to activate again. Ben transformed into Feedback and used his energy absorbing and redirecting powers to quickly defeat Malware. During the fight (as presented and revealed in both Of Predators and Prey: Part 1 and Of Predators and Prey: Part 2), it is revealed that Malware had successfully created a blueprint by absorbing Omnitrix.

In Of Predators and Prey: Part 2, Ben battles Phil who is being used as a test subject for the Nemetrix.

In Malefactor, Ben, along with Max and Gwen, visit the Plumber base in Mt. Rushmore. There, they are attacked by Malware who is seemingly defeated by a Tachyon Cannon. However this just transforms him into a more powerful version of him. He gets defeated, although, he was just a distraction so that Khyber can sample a rare Psycholeopterran.

In Ben Again, while battling Eon, 11 year old Ben's mind gets switched with his 16 year old self. As 16 year old Ben, he finds the clues laid down by the 16 year old Ben who is inhabiting 11 year old Ben's body. 11 year old Ben manages to get his body back and defeats Eon.

In Showdown: Part 1, because of his constant use of Feedback, Azmuth comes to Earth to warn Ben that this is affecting his other transformations. Ignoring him, Ben prepares to fight Malware who has returned. This results in Feedback being destroyed and Malware being seemingly killed when he is overloaded by the Omnitrix's energy.

In Showdown: Part 2, Ben and Gwen exit from the Rust Bucket after Max had returned Ben back into the neighborhood that his house is located inside of. Ben is shown to be depressed and upset about losing Feedback and Max tells Ben to head inside. Azimuth eventually arrives and talks with Ben and explains to him that he never learnt anything from winning and that losing Feedback was hard for him. Ben says that Feedback was like a part of him but Azmuth says that Ben could learn something from losing Feedback. Ben eventually forgives his future self and this allows 16 year old Ben to regain Feedback.

In Special Delivery, in a flashback, Ben accidentally throws Mr. Baumann's truck into space as Way Big during a fight against Dr. Animo and his Mutant Mosquito.

In Mud Is Thicker Than Water, Ben tricks Gwen into disliking their cousin Lucy by putting sludge all over her comb.

In The Vengers, Ben saves the people from an exploding building and captures Kangaroo Kommando as XLR8. With this Ben makes new enemies, in the forms of Captain Nemesis who sees him as a rival and Will Harangue who sees him as a vigilante.

InEvil's Encore, Ben, Gwen and Max encounter and defeat Dr. Animo again after he managed to take control of the Plumber's base that was located inside of Mt. Rushmore and tried to use the Plumber satellite network in order to spread his mutation ray over the Earth.

In Weapon XI: Part 2, Ben, Gwen, and Max fight the Amalgam Kids and Kevin who once again absorbs the Omnitrix's feedback and undergoes another mutation that transforms Kevin into an alien hybrid that consists of the other 10 aliens Ben unlocked in the original series. Argit managed to knock out Kevin and him, Argit, and the Amalgam Kids return back into the Null Void.

In From Hedorium to Eternity, Ben, Gwen, Lucy, Cooper and Jonesy meet Kevin underground and together stop Zs'Skayr and his Ectonurite minions from taking over the planet. Ben learns to trust Kevin but he once again gets stucked in the Null Void. Ben and Gwen had never encountered him again until four years later when they have developed into teenagers.