Ben, Gwen, and Kevin are summoned to Plumbers Academy to go under training. They create a good friendship with an alien named Tack and Ben dislikes the drill instructor, Magister Hulca, that is being targeted for revenge by a menacing Tetramand.

Gwen must juggle things around, in which she has to help Ben and Kevin recapture Dr. Animo, fill out invitations for her mother Natalie’s family reunion, help Kevin get into school, finish exams, and go to her best friend Emily’s piano performance.

Following a visit from Paradox after a fight with Eon, Ben 10,000 from an alternate future arrives twenty years from the future to seek the aid of his past counterpart in tracking down Eon. It is revealed that Eon is actually an adult Ben from an alternate world, and that he wants to destroy all […]

Old George brings the Forever Knights in one group to vanquish every alien being on Earth.

Simian accidentally unleashes a Xenocyte Queen which orchestrates an invasion of the Arachnichimps’ planet. When Eunice goes missing, Ben, Gwen, and Kevin end up helping Simian liberate the Arachnichimps’ planet from a DNAlien version of the Arachnichimp Mizaru.

Techadon robots go after Ben on orders from Vulkanus to attain the Ultimatrix. Gwen and Kevin go across space to prevent Vulkanus from getting what he is after.

Albedo profits from Ben’s fame and creates a play about him with the help of three alien actors based on several of the extraterrestrial forms in Ben’s Ultimatrix.

Elena Validus and the nanochips return and impersonate Julie while the real Julie is at a tennis tournament overseas. Ben does not catch onto this until the very end when the real Julie returns and causes Elena to realize that she had never really loved and cared about the real Ben in the first place. […]

The ultimate aliens inside Ben’s Ultimatrix demand their freedom and end up sucking Ben into the Ultimatrix. While Gwen unleashes her astral projection (in the form her innermost anodite self) enters the Ultimatrix to help Ben, Kevin travels to planet Galvan Prime to convince Azmuth to help.

The gang look into the Pacific Garbage Vortex when some people have gone missing. When they arrive, they find the missing people and two agents sent by Colonel Rozum while dealing with giant seagulls and a sentient trash monster.

Ma Vreedle plans to spawn an army of Pretty Boy Vreedle clones, which could dry up Earth’s oceans.

Azmuth reveals in his memories how Old Sir George had acquired the great and mighty sword of Ascalon, and how he had sealed Diagon the first time millennia ago. In addition, he reveals the real reasons for his eventual creation of the Omnitrix and Ultimatrix.

Techadon Weapon Master Number 13 arrives on Earth and demands to have the Ultimatrix. A malfunction grants Gwen and Kevin the forms and unique abilities of some of Ben’s aliens.

Dr. Animo returns with a plot to transform eggs into pterodactyls.