Ben 10 Ultimate Alien: Alien Kombat

 Plot

Ben is invited to a fighting competition for celebration of defeating the most powerful villains in the galaxy. (Like Vilgax and Aggregor.) He takes part in the competition and ends up bringing Kevin along to enter as well. But, Vulkanus and Sixsix are also in the competition. Ben and Kevin learn they want to steal the trophy and destroy the planet with the greatest fighters and heroes on it. Can they be stopped in time?

This an hour-long episode. Ben and Kevin are the main characters in this special.

Heroes
Minor charactors
 * Ben Tennyson
 * Kevin Levin
 * Tetrax Shard (voiced by Dave Fennoy): A Petrosapien Omnitrix/Ultimatrix Guardian and a friend of Ben, he is part of the competition, too and represent his race of Petropia.
 * Ziro Gree (voiced by Dante Basco): An alien hybrid Polar Manzardill that represents for his people of X'Nelli. He is cool and easygoing. He becomes good friends with Ben and has a grudge against Flarez. He resembles a humanoid version of Articguana, and mentions his father is a Polar Manzardill and his mother is human. He wears a blue headband, fingerless gloves, baggy pants and shirt, yellow eyes and spiky hair.
 * Kling (voiced by Kevin Michael Richardson): A Transylian that looks like Dr. Victor. He has green eyes and three scars on his chest.
 * Master Magma (voiced by Steve Blum): Master fighter Pyronite and Flarez's father. One of the judges for the competition. He tries to teach his son about honor.
 * Hype Zone (voiced by Tom Kenny): A famous celebrity Citrakayah, and the same race as Fastrack. He was Kevin's last opponent and was interrupted by Vulkanus. Kevin mentions him as a showoff. He is shown to make an entrance, as he does a backflip in the arena.
 * Lepidopterran Fighter: Defeated by Ben.
 * Tetramand Fighter: Defeated by Ben.
 * Arachnachimp Fighter: Defeated by Kevin.
 * Isis Talon: A female Appoplexian and Ziro's girlfriend that came watch his matches. She resembles Intress from Chaotic: Dawn of Perim. Like Rath, she gets very mad at anyone that hurts Ziro. Vulkanus experiences her wrath for trying to destroy the planet and knocking out Ziro.
 * Azmuth (voiced by Jeff Bennett): Creator of the Omnitrix and one of the Judges for competition.

Villains

 * Vulkanus
 * Sixsix
 * Reaptile (voiced by Frank Welker): A mutant Merlinisapien wearing a ninja suit and red eyes, he is Ben first opponent in the competition and later work with Sixsix to steal trophy and destroy the planet.
 * Flarez Magma (voiced by Tom Kenny): A young, dishonored Pyronite that does what it takes to win. He is a high school bully and picks on Ziro for being half-human.
 * Midite: A half-Ectonurite and half-human. She has the same powers as Ghostfreak and was Ben second opponent to face off. At the end, she wanted to joined the Plumbers and her eyes turn pink, leaving with Ben and Kevin. She is a pale goth girl with black hair and purple eyes.

Aliens Used

 * Wildmutt (2x)
 * Shellhead (debut)
 * Alien X (mentioned and still set back on locked mode)
 * Eyeguy (first reappearance since original series)
 * Spitter (first reappearance since original series)
 * Rath 
 * Fasttrack
 * Humongousaur
 * Ditto (first reappearance since original series)
 * Benmummy (accidental transformation; selected alien was Goop)
 * Benwolf (first reappearance since original series)
 * Eatle (second appearance in Ultimate Alien)
 * Clockwork (first time selected by 16 year old Ben)
 * Waybig

Trivia
 * This episode and the fighters featured in it are based on Mortal Kombat.
 * Ziro Gree is based Liu Kang with Sub Zero fight moves and powers, Hype Zone is based Johnny Cage, Kling is based on Jax, Reaptile is based on Reptile and Flarez Magma is based on Scorpion. 
 * Only five aliens from the original series return and are used this episode.
 * Steven Jay Blum returns as Master Magma, a Pyronite (in the original series, he play Heatblast, Ghostfreak and Vilgax.)
 * Sixsix returns from the original series and helps Vulkanus again.