The summer finally ends. Ben and Gwen have to go back to their normal lives. Grandpa Max tells Ben to keep the Omnitrix a secret from everyone, even his parents. Ben agrees, but Vilgax arrives and he'll stop at nothing to get the Omnitrix.

The Megacruiser flies solo in space, and inside Kevin examines the giant ice block found in space. Inside the mass, held Vilgax, and Kevin underestimated his current situation. He was very much alive and well, and they soon create a partnership after learning that they were both after the same person. On Earth, Ben plays around with the Omnitrix, hoping to find a better way of controlling it. Eventually, he finds the master control of the Omnitrix, giving him the ability to alternate between aliens, as well as prolong his duration with a form. Although his discovery has given him a stronger advantage, will it be enough to stop the danger that lies ahead?

Vilgax tries to get the Omnitrix for himself while Grandpa Max's strange past becomes known, causing a showdown between Vilgax and the Tennyson family.

Ben, Gwen, Cooper and Grandpa Max face their last battle ever against the villains they have encountered and they will battle to get the world's most powerful energy source.

The Forever King sets his plan in motion and recruits the most powerful enemies Ben has ever faced in order to steal the world's most powerful energy source.

At a city, Ben, Gwen, and Grandpa Max are waiting outside a video game store to purchase the newly-released Sumo Slammer video game. Gwen and Grandpa Max go the book store, but when they return to check on him, Four Arms comes out of the store by force. They return to the RV, and find that Ben is already there. Gwen yells at Ben for what he's done, but he has no clue of what she's talking about. But as she gives direct evidence that Four Arms was attacking the city, Ben heads out to find the perpetrator, using the identity of his aliens to ruin his current reputation as a hero.

A terrorizing nightmare of Ghostfreak is half the trouble for an unnerved Ben, as a tour of an important academy that Gwen wishes to attend is disturbed by the uncanny alien's manifestations and the antics of Acid Breath, Frightwig, and Thumbskull.

During a battle with Dr. Animo, the Omnitrix is accidentally set to self-destruct. In order to stop it, Ben, Gwen, and Tetrax travel across space to track down the Omnitrix's creator, Azmuth.

Ben meets a mutant who can absorb any form of energy and may be after the Omnitrix.

In the middle of nowhere, Ben, as Diamond Head, fights Kevin 11, who is still in his mutated form. As they fight, they are taken to a ship, where a battle between different aliens are held. But when a mechanical droid named Slix decides to create a bond with Ben and Kevin as a team, they immediately turn his idea down. But with no choice, they must find a way out. Will Ben and Kevin learn the importance of teamwork?

Ben is pursued by three bounty hunters sent by Vilgax to steal the Omnitrix.

While on a desert highway, the RV gets stolen by a group of modern-day pirates, who use it to go on a robbery.

When Ben accidentally breaks Gwen's laptop, he participates in the "Ultimate Wrestling Competition" as Four Arms to get the prize money for a new laptop to replace Gwen's broken one.

Ben discovers an evil circus that's headed by a psychic vampire clown named Zombozo.

Enoch and the Forever Knights return, putting Ben in a dream world where he's tricked into having the perfect day. However, his dream quickly turns into a nightmare.

In the future, Ben gives his son, Ken, an Omnitrix for his 10th birthday. However, Ben will have to learn to trust him with that power.

Average kid, ten year old Ben Tennyson, his Grandpa Max and his cousin Gwen's summer of adventure takes an odd turn when Ben discovers a watch like object that has been jettisoned from alien spacecraft high above the Earth.

Ben battles a sorcerer who possesses a number of charms, and Gwen suddenly becomes a superhero when one of the charms falls into her hands.

After the battle with Vilgax, Grandpa Max retells his story to Ben about his past. He was with an organization that was not known to exist, referred to as "The Plumbers," a group of people who track down extraterrestrial life. Meanwhile, they meet Phil, an old partner of Grandpa Max. But they soon find out that he steals a device, called the Null Void Projector, to selfishly use it to make money by appearing to capture aliens that he alone released himself.

In this "how 'bout?" episode, Gwen gets the Omnitrix and the power that comes with it.

When Ben and Gwen argue over a birthday party to occur in the next few months, Grandpa Max is distracted by their quarreling and almost hits a young boy camper. To ensure the boy's life, they head to Camp Opinicon, only to find no people around. As they investigate the premises, they find twins, whom were also hiding from something that may have a connection to the lifeless camp. Grandpa Max readies to leave the area with the children, only to find that the RV's engine is clogged with a mysterious fungus. While the kids take in shelter in a nearby cabin, Grandpa Max is captured. Now Ben must come to the rescue to discover a new alien form, as well as a way to destroy the evil alien Myceloid Monsters and their Fungal Master, and learn the benefits of what sharing can do.

Hex's niece, Charmcaster, enters the underground prison he's held at to release him out of his cell. With her help, Hex was able to regain most of his powers after being given his magical staff. Meanwhile, Ben, Gwen, and Grandpa Max head to a magic convention held in Las Vegas, and in there, Gwen finds the legendary Keystone of Bazell. With it, she gains the powers of Lucky Girl once again, but will it last after finding out that Hex and his niece are after it?

Ben clashes with a female gang member who's become part cyborg.

The Tennysons arrive at a swamp, where a festivities of Gatorfest start first thing the next day. Gwen finds Ben playing around with the Omnitrix, and she warns him that it may create unusual problems. Without heeding Max and Gwen's warning, he pops the face out, and the Omnitrix acts up. Right away, something was wrong, though it was gone unnoticed, at least, until the next day. Gator-fest was going along well, but the giant frog of Dr. Animo comes in to disrupt it. Dr. Animo has returned, and he wants to take revenge on Ben. But when Ben goes alien, he transforms into a hybrid alien with unbalanced attributes. Will Ben ever learn his lesson in listening for a change?

Ben gains another Omnitrix hero to use, which he calls Ditto. Gwen can't stand being around the multiplying Dittos, and they end up giving her headaches. The Dittos, though, prove to be real helpful against Dr. Animo and his multiplying Stinkflies after he extracted some of Ditto's DNA.