Takes place after Omniverse when Vilgax, Hex, Charmcaster and Scarecrow broke out of the Null Void and sent Ben Tennyson back in time five years. Azmuth is able to throw his new creation, the Omnitrix II through the portal. Ben has to use the Omnitrix to defeat the bad guys five years before they throw him in the portal!
Ben Tennyson - The user of the Omnitrix II. Was sent back in time 5 years so is now 12 years.
Kirby An - Ben's new partner who is an Osmosian.
Pyro - A Pyronite who is like Heatblast.
Tetrax - A Petrosapien who helps Ben. He is like Diamondhead.
Sugilite - A Crystalsapien who is the DNA sample for Diamondhead.
Vilgax - The returning antagonist.
Hex - A returning antagonist.
Charmcaster - A returning antagonist
Scarecrow - A new antagonist.
Negameto - A new antagonist that when the Omnitrix scans him, Ben gains a new alien.
Rock Monsters - Charmcaster's Henchmen.
Fire Monsters - Scarecrow's Henchmen.
Gametos - Copies of Negametos who are Negameto's Henchmen.
Season 1 - Villains known as Scarecrow, Negameto, Gametos and Fire Monsters attack Ben. Can Ben defeat them? A new hero helps Ben in some episodes.
Season 2 - The unknown hero reveals himself to be Kirby An, Ben's childhood friend. They team up and create Team Tennyson while fighting Charmcaster, Hex and the Rock Monsters.
Season 3 - The devastating Vilgax returns in Season 3 as the main antagonist. Can Ben defeat him and bring peace?