Psyphon turned out to be quite Badass, so props to him too. Especially when he made Armodrillo lose control.
Points to Ben though for electrifying himself in order to make sure he didn't hurt anyone. Seeing how the electric shocks still affected him when he went back to human, that took guts.
Ben has difficulty with using his new alien Gravattack, and is fighting a mech, while still learning about Gravattack's powers. He wins anyway.
Even better? At one point he pushes the mech down to the ground, but he's not worried about that. He's using the gravity powers because he knows the docks won't be able to handle that much mass and thus the mech will sink into the water!
And the best part? When he's about to be attacked by missiles, they don't hit him. They circle around him. Ben says it best.
Gravattack: I have my own orbit? THAT is pretty cool!
And then he throws all of them on his opponent at once.
Young Ben's defeat of Malware as Diamondhead in "Trouble Helix", especially the final dialogue:
Ben finally controlling Alien X and reconstructing the Universe when it is destroyed due to the Annihilarg.
In "Hot Stretch", Ben transforms into NRG and begs not to let the Kraig-ho remove his suit. They do. And then he proceeds to eat the fusion engine!
Also from "Hot Stretch", Rook's stand against the Kraig-ho is pretty awesome. He's out of his element, overheating in the Kraig-ho's own environment, but he never stops fighting.
Villainous one for Khyber in "Of Predators and Prey" for actually beating Ben!
But then that was turned around as Ben and Rook made a plan so that Khyber would deliberately capture Ben and then Rook would follow him to where Khyber was!
Ben taking down Humungousaur's natural predator... as Grey Matter. Utilizing the same nerve pinch Khyber used to subdue Rath.
Despite being stuck as a useless aliens in "Outbreak", Ben uses his knowledge of his forms to help Rook and the other Plumbers take down the baddies, who have been transformed into his aliens.
Max and the plumbers taking down Dr Psychobos robotic worms. At first their shots do nothing, then Blukic and Driba give them improved Ammo, and they destroy the rest of the worms.
Practically every fight involving Ben in "Gone Fishing". After the Badass Decay he suffered in previous episodes, Ben finally shows why he is the saviour of the universe.
The scene in "Malefactor", where Ben overcomes the illusion created by Hypnotick of being surrounded by adoring fans, by reminding himself of what being a hero is really all about.
In "It Was Them", Rook has attained a bomb to take out Dr. Animo's ants, which have him and Ben drastically outnumbered and mildly outmatched. He states that he can detonate the bomb to destroy the giant ant hill they're in, the ants, him and Ben, in addition to several populated areas. Ben shows no shock or alarm until Rook mentions the populated areas. Think about that for a second.
"Ben Again" has several:
Paradox vs. Eon. Bonus points for seeing Paradox angry for once.
The final battle features 11 year old Ben as Articuana and 16 year old Ben as Wildvine holding back Eon, while Old Gwen and Young Gwen preform a spell together to free Paradox.
"Showdown Part 1" might as well have been called "Azmuth is Awesome". To expound trapped with Khyber's hound transformed into the most dangerous predator the Galvan race ever had, he refuses to treatDr. Psychobos as anything more than a nuisance. When he learns that he can't teleport out, he instead teleports Ben and Rook in. After learning the hound is controlled by Khyber's whistleing, he uses Rook's Omnitool and a bone to make a flute, and keeps the hound transforming to disrupt its attack. And then to cap it all off he figures out how to turn the hound into a Cerebrocrustacian's perfect predator and makes Psychobos his bitch. Damn.
There's also 11 year old Ben overloading Malware and nearly killing him.Don't get Ben mad.
The finale of "Showdown Part 2" is a crowning moment of awesome for Ben, Azmuth, the Mechamorph race, Kevin, and Khyber's pet who all help take Malware down once and for all. The real crowner has to be Ben regaining Feedback and Feedback than procceding to drain Malware of all his power.
Vilgax, despite the fact he gets almost no fight scenes in "Vilgax Must Croak", manages to survive the episode, outplay everyone involved, and ultimately wins.
He gets one right at the start of the episode. He's considered so dangerous that Incarceron is cleared out of all other prisoners and staff. He was going to be the only prisoner because they were so afraid of his ability to manipulate others.
Way Big VS Way Bad(A mutated Way Big).
After that, Way Big VS Incursion ship.
Julie with Powered Armor vs Princess Looma. Julie delivers the Knock-Out with her tennis skills.
It's not as noticeable as the rest of the examples on here, but in Store 23 the local Six-Six has placed an arm bomb on Ben 23. Now while Ben freaks out as this, Ben 10 as XLR8 immediately springs into action, using the super speed to run through every possible combination it could have to come off, and with a second to go rushes faster than normal, places the bomb near Six-Six and gets back in time to tell 23 to cover his ears. This is followed by the older Ben taking on both Six-Six and Tetrax at once.
Sandra Tennyson standing up to and stopping Ma Vreedle from blowing up the sun.
Will Harangue getting mutated into an alien freak.
Crashhopper, the Butt Monkey of Ben's alien forms, taking down Psyphon's gang in "Mud Is Thicker Than Water", followed up by taking down the stolen tank Psyphon is using.
Upgrade(Ben) fusing with Kevin's car for a Humongous Mecha battle in "Otto-Motives", beating OTTO, who had fused with the Proto-Truk and 4 rare alien cars.
Argit of all people defeating Ultimate Spidermonkey.
Kyhber revealing that he has a new henchanimal, Ditto's natural predator, a reddish-purple and black cat-like creature that has the same Me's a Crowd ability its prey has. Ben, who had the bad luck of turning into Ditto, manages to stay one step ahead of it for a while.
We finally get to see Atomix, the last of the aliens mentioned in "Ken 10", and he does not dissapoint. A large ham flying brick with energy powers, he takes down both Albedo's Ultimate Humongasaur and Ultimate Spidermonkey forms and makes it look easy.
Word of God says he is the 2nd strongest alien, after Alien X. Considering Alien X's condition, this seems to indicate how powerful Atomix is and how much we can look forward to see.
Ben is able to control Ghostfreak in the very same episode. Given all trouble he's had with this before it's great to see him be able to finally do it. Even if it's implied to be the chains that Ghostfreak now has on him that's keeping him from going berserk.
Also, Ben taking down a magic golem as a human, since the Omnitrix is stuck on Ghostfreak and he doesn't want to take any chances. He uses his agility to trick it into bringing a giant pillar down on itself.
"Charmed I'm Sure": Swampfire's new form proceeding to take control of Ghostfreak's army of plant-like monsters and fight a superpowered Charmcaster.
Heck, superpowered Charmcaster, complete with golem mech armor. Ben calls it "the coolest thing ever". Then after Charmcaster attacks them with: