A rage-filled Ultron quickly flew towards Sunset in order to destroy her once and for all. However, just as he reached her, Twilight used her magic to force the drone holding her at gunpoint to fire at one of Ultron's rocket boosters, causing him to lose control and crash to a nearby fast food restaurant. Then, she used the drone to fire at the other drones, taking them out and liberating her friends. Ultron quickly recovered, but the girls came right between him and Sunset.

"Like I said, we'll stop you together."

"I think you mean, you'll perish together."

"Just try us, scrap pile!"

"With pleasure!"

He unleashed another laser beam from his mouth and even though Rarity tried to block it with a diamond wall, the blast made the blow in just a couple of seconds and all the girls (except Sunset) were pushed away by the impact of the explosion. Pinkie recovered first and threw a bunch of explosive sprinkles at Ultron to no avail. Just as Ultron tried to crush her with his bare hands, however, Rainbow pushed her away and she threw some more sprinkles at Ultron. Even though they didn't damage him, they surely pissed him off. He emitted another laser beam but Rainbow saved Pinkie again. So, they started to do this in a loop. Pinkie would throw some sprinkles, Ultron would try to blast her, Rainbow would push her away, she would throw some more sprinkles, and the whole thing would start over again. While they weren't hurting Ultron, they were most definitely distracting him really well. Then, Applejack and Rarity recovered and decided to help out. Rarity created a huge diamond ball and Applejack punched it towards Ultron. It hit his head, causing him to back away a bit before trying to blast them too. Thankfully, Rainbow managed to get them to safety at the last second. So, another loop began. Pinkie would throw some sprinkles, Ultron would emit his laser beam at her, Rainbow would push her away, Rarity would throw a diamond shield, Ultron would try to blast her, Rainbow would get her to safety, Pinkie would throw some more sprinkles, and the whole thing would start over again. Seeing that the distraction was going well, Applejack helped Twilight and Fluttershy recover, and all three rushed over to Sunset's side.

"How's the sabotage going?"

"Not well. I ripped out some cables and pushed every single button but it's still charging."

"Then, we need to find the right combination of buttons to shut it down. Fluttershy, did your little friend make it inside."

"Yes, he'll be at his destination soon."

"Excellent. Then all we gotta do is to try every possible button combination."

"There's nearly twenty buttons here."

"Then, we have no time to lose. You try the left side and I'll try the right side."

"Fine."

They immediately started pushing buttons as fast as they could.

"Is there somethin' I can do to help you guys out?"

"No, we're good. You can help the others distract Ultron, though."

"Sweet! I've got a score to settle with that rust bucket."

She rolled up her sleeves.

"Applejack, no! Don't take him head on!"

It was too stop Applejack, though. She immediately jumped towards the distracted Ultron in order to bring him down, but he quickly incapacitated her with a punch to her gut.

"AJ!"

As Rainbow rushed towards Applejack's side, Ultron took her out with his laser beam. Then, she emitted another blast towards Rarity and even though she tried to protect herself with a diamond shield, the beam quickly shattered the shield and the impact of the explosion pushed her to a concrete wall, incapacitating her. He then, attempted to blast Pinkie but Twilight managed to lift her up and push her away at the last second. As a furious Ultron turned his attention towards Twilight, Rainbow tried to hit him again with her super speed and while she did manage to land a punch, the strength of Ultron's armor nearly broke her hand.

"OW! Okay, that hurt!"

"Oh, you haven't suffered enough."

He promptly stomped on one of Rainbow's legs. breaking it and making her scream in intense agony.

"There. You won't be running for a good long while. Still, this doesn't feel like enough punishment for you."

He grabbed her by the throat, lifted her up, and began to strangle her.

"Out of all the magic-powered teenagers I had to deal with; you're, by far, the most persistent and therefore; the most tiresome and irritating of them all! I'm going to enjoy every single second of choking the life out of you!"

He started to squeeze her neck even tighter.

"HANG ON, RAINBOW!"

Rarity threw a huge shield towards Ultron's hand holding Rainbow. However, he caught it with his other hand and threw it back with such a trajectory that it hit not just Rarity, but also Pinkie and Fluttershy. He then turned to the remaining girls.

"This is the price you pay for denying my superiority. Don't worry, though. Once I'm done with her, you're all next! So, in a way, you'll all be together in the afterlife, if such a thing even exists!"

He was extremely close to killing Rainbow when suddenly, he let her go.

"What's happening? My head is detached? This isn't good!"

He tried put his head back in its place, but it didn't work.

"What is this? What is this, please?"

"What's happening is that my new virus worked! When Fluttershy was distracting you with her birds, one of them dropped a flying ant through your mouth. It was carrying a small computer chip that contained a nasty virus that I recently developed. Once the ant inserted the chip to your cerebral matrix, the virus inside caused your head to be detached from the rest of your body. Now, you're finally vulnerable! Sunset, help Pinkie get up. Applejack, you're ready?"

"Born ready, Twilight!"

As Sunset rushed to Pinkie's side, Twilight lifted up Applejack and threw her right towards Ultron's head. Applejack, then punched his head with all her strength and the head promptly flew off Ultron's body. Meanwhile, Pinkie managed to get back on her feet thanks to Sunset and after being informed about the situation, she poured her entire supply of remaining sprinkles to Ultron's open neck, causing his body to blow up from the inside. The eyes on his head finally faded to black.

"WE DID IT!"

"Not yet. We still have to figure out how to shut down this machine."

"But we tried every button combination possible, Twilight. And it's 99% charged!"

"Have you tried cutting the red wire?"

"Come on, Applejack. It can't be that simple."

"Well, I'm gonna try it anyway."

"Wait! Don't just... "

As soon as Applejack pulled out the wire, however, the machine stopped working.

"How?"

"I guess Ultron knew we would think that the red wire was too obvious and so, connected the shutdown sequence to it."

"Oh. That makes sense, I think."

"And now, the day is saved! Let's go and celebrate it with a save-the-world party!"

Then, they all heard a groaning sound.

"RAINBOW!"

She and Pinkie immediately rushed to Rainbow's side and after Twilight and Sunset helped Rarity and Fluttershy helped get back on their feet, they all gathered around her with worrying looks.

"Hey, guys. Did we win?"

"We sure did, sugarcube. Don't you fret, now."

"Great. So, what are we waiting for? Let's go and celebrate."

"You can't be serious, darling! We need to get you to a doctor, right now!"

"I'm fine! It just hurts a little. I can still party!"

"Please, Rainbow. Let us help you."

Rainbow let out a deep sigh.

"Fine! Only for you, Fluttershy!"

They all laughed and helped Rainbow up. However, as they began to leave, they noticed a damaged but still functional Ultron drone crawling towards them.

"Don't think yourselves victorious just yet. I can still escape through the internet and come back stronger than ever."

"Actually, you can't. The virus also blocks every possible computer system on the planet from your data signature. So, even if you transfer your consciousness there, you'll be just bumping into a series of walls and be forced to return to this body."

"Then, it looks like this is the end for me. I have failed in my mission. I have failed the world."

"Trust me, the world will be a lot safer without you."

"It's doomed without me! How can it be safe with vermin like you infecting it with violence and chaos?"

"It may not be a perfect world, but we all know you would've made it a lot worse."

The drone tried to shoot them with its arm cannon, but it was instead crushed by a giant diamond created by Rarity and immediately shut down.

"Well, good riddance! Now let's get out of here and bring Rainbow to a doctor."

"We're still gonna celebrate, right?"

"Well, of course, darling. As soon as you're fully recovered."

"Don't worry, Dashie. We'll throw the biggest save-the-world party ever. Pinkie promise!"

"But what about Rainbow's welcome-home party? Should we do it before or after the save-the-world one?"

"How 'bout we just do the save-the-world one? I'm sure Scootaloo would wanna throw you a welcome-home party as big as the one you threw for her."

"Yeah, it will be undeniably, unconditionally, awesome if she's the one throwing it."

They all laughed and walked out of the mall just as a beautiful sunset was taking place.

Author's Note

Well, this is the end of the story. I hope everone enjoys it and if it gains a lot of positive reaction, I might write another story focusing on Brainiac (Ultron's DC counterpart). It will be set in the pony world.