A/N: This is a requested sequel to Ponies Unite! from retro mania. There will be three parts. It's a mix of the old MLP series and the new MLP series. I'm not an expert on old MLP - forgive me. Enjoy!

Villains gathered in a secret lair, all surrounding a large portal. It was glowing green and showed an image of a colourful village full of ponies. But the villains weren't interested in that. They were interested in the villains of that world. Tirek, the leader of all the villains, wanted to contact his other self from that world. He was hungry for revenge on those pathetic ponies - the ones from his world and the other Tirek's world. He'd gathered every villain together in his world and now they were going to contact the other Tirek and gather every villain they had, and destroy those ponies.

"Ah," The Tirek of this world managed to contact the Tirek of the other world.

"Are you sure this will work?" Catrina asked.

"Yes," Tirek replied. The portal showed a prison: Tartarus, where the other Tirek was trapped.

"Looks scary." Zeb commented, eyeing the prison. It had three crystal pillars, holding various villains behind gleaming bars. One of these was the other Tirek. In front of him was a stairway, then the three-headed dog, Cerberus.

"I've never seen a three-headed dog before!" Gock gasped. Crunch growled at Cerberus; he was another dog, after all.

"That Tirek really does look like you." King Charlatan commented, making a face.

"Silence, whilst I speak to myself," Tirek commanded. He moved the portal closer to his other self, who was writhing in agony. Cerberus growled. "Do not make noise - we may disturb the hound."

"Yucky dog, anyway." Princess Porcina snorted. Squirk went near her. She shrieked. "Get away, octopus!"

"Silence!" Grogar repeated - he was a suck up to the leader because, quite frankly, he wanted to be the leader himself. Tirek got the attention of his other self; he looked up in surprise.

"Greetings," the Tirek of this world spoke. "I have a question." He grinned darkly. "Are you ready for revenge?"

The main six were sitting in Twilight Sparkle's castle, having a banquet of food cooked by Pinkie Pie herself. It was incredibly well-made; everypony was chowing down.

"Pinkie, this is spectacular!" Rarity admired. "You really outdid yourself!"

"Thanks!" Pinkie Pie giggled in response. "I put a whole lot of effort into this!" With a long, orange tongue, she slobbered up an entire cake. No one decided to question the physics - it was just Pinkie being Pinkie. They continued eating their food, not noticing the various villains approaching Twilight Sparkle's castle. Old villains, new villains. They crept into the castle, stealthily unnoticed.

"Whoo-ey!" Applejack grinned, finishing a slice of cake. "You did well again, Pinkie."

"Truly awesome!" Rainbow Dash agreed. She made a face. "Well, not as awesome as me, but up there." Pinkie Pie only giggled. Suddenly, her tail started vibrating; an expression of worry crossed her face.

"What is it, Pinkie?" Twilight Sparkle asked, looking up from her donut.

"My… My Pinkie Sense!" Pinkie Pie answered, her voice shaky. "Something bad's about to happen!" And, with that, the villains lunged onto the ponies. They knocked them all out before they could fight back and dragged them away.

"Excellent," the old Tirek congratulated the new Tirek. "We have them." The ponies found themselves trapped within Tartarus; they were surrounded by crystal-white bars. Cerberus was ahead, a deep growl in its throat. They gasped in horror. Arabus flew around them, making sure they were secure. He gave a nod to his comrades.

"They are trapped," Catrina observed with satisfaction. "They can't escape."

"Wh… who are y'all?" Applejack asked. Suddenly, she gasped. "Wait a second…"

"You're… you're the Tirek from that other world!" Twilight Sparkle exclaimed. "You… but we defeated you!"

"Well, little ponies, I've returned," Tirek grinned. The G4 Tirek stood next to him, sharing his smirk. "And this time, everyone is here!" Villains that Twilight Sparkle and friends recognized and didn't recognize were behind them. The ponies gasped in horror. Fluttershy almost cried and Rarity passed out.

"We're not afraid of you!" Rainbow Dash growled. She tried to fly, but the power from the prison kept her grounded. "What do you want with us!?"

"Oh, nothing much," Tirek answered. "Just… a little revenge."

"You won't be escaping." Catrina added. "Oh, by the way, my name is Catrina. Nice to meet you… and watch you perish."

"Your world is doomed!" the Flores chirped sequentially.

"Talking flowers?!" Rainbow Dash asked. She screamed in horror.

"Say bye!" the Dragon Gang cackled. The villains laughed as the ponies realized the horror of the situation. They were doomed.

"No," Twilight Sparkle growled under her breath. She faced her friends. "There is somepony who can help us. If the villains from this world are contacting villains from the other world, we can contact our allies from their world."

"Oh yeah!" Rainbow Dash cheered.

"How do we contact them, then?" Applejack asked, raising a brow.

"Ooh! Ooh!" Pinkie Pie waved her hoof. "I can just contact their dimension! No biggie!"

"You can do that?" Twilight Sparkle asked, shaking her head. Sometimes she was still surprised by Pinkie Pie's weirdness.

"Yep!" Pinkie Pie replied. "They gave me their number!" She dug a hole in the ground and stared at it, her eyes all swirly. A small, green portal opened up, revealing the land of G1 - the ponies immediately recognized it. They saw their friends there, simply having lunch - just like they were. Their human friends Megan, Danny and Molly were there, too. "Hey!" Pinkie Pie spoke up.

"Hey!" Firefly yelled back. Everyone turned to the screen.

"Twilight Sparkle!" Twilight gasped, grinning. "It's nice to see you!" Posey gave them a shy wave.

"Are these the friends you were talking about?" Megan asked. She grinned. "Hi, I'm Megan. This is Molly and Danny. It's nice to meet you!" She pointed at the other humans. They waved.

"Introductions are nice and all, but we're kinda having a problem here," Rainbow Dash spoke up, frowning. "The villains from your world and our world joined up and now they want to destroy everything."

"And they trapped us here in this awful place - Tartarus!" Rarity exasperated.

"That's no good," the Applejack from the G1 world commented, shaking her head. "We'd better make ourselves a rescue plan!"

"You got that right!" Danny agreed, standing up. The G1 Spike stood up as well. "We'll have to come over and rescue you!"

"But how do we get to Tartarus?" Molly asked. The portal began shimmering.

"Uh oh, looks like we're running out of time!" Pinkie Pie giggled. She stared at the G1 characters. "I think there's a portal that lets you come to this world. Find it and you can come here!"

"But where…?" The green portal faded away. The G4 ponies stared at the now-empty space.

"Let's hope they can find us," Twilight Sparkle sighed. "They could be our last hope."

The ponies and humans, indeed, found the portal. It was underneath a volcano, where Lavan resided. They leaped inside, entering the G4 world. There was no time to admire it, however. They needed to find Tartarus.

"It'll be around somewhere," Twilight said. "Underground, most likely."

"Awesome!" Firefly cheered. "We're going under!" Tartarus, in fact, was in another dimension entirely. Pinkie Pie contacted them again for a brief second, telling them where to go. They went to Canterlot Castle and found the portal, deep within the hidden libraries. They jumped inside, entering Tartarus.

"Okay," Megan spoke up. "Now to rescue-" But she never finished because they were ambushed by the villains.

"Say goodnight, Megan." Catrina commented. The ponies and children realized they had been ambushed.