Here's how killing the other villains and Tirek goes in Wrath of the Century.
[When Thomas lands they only find a few of the other villains]
Thomas: Cinders and ashes!
Discord: [as Hooper (in his version)] You think this is over? All your little stunts did was to buy them time!
Queen Chrysalis: You may of destroyed our army, but we will prevail but you won't!
[just then a Chinook Chopper flies in]
[it crashes onto the ground and its pilot reveals to be the T-850]
T-850: I'm back.
Nightmare Moon: You!
[then the door starts to close as the T-850 then jumps forward and it open]
T-850: GO!!! NOW!!!
[they run for it]
Cadance: Thank you.
T-850: We'll meet again.
Cadance: [nods and takes off running]
[but before she can escape Chrysalis grabs her tail]
Queen Chrysalis: You won't get away that easy! [pulls her back]
Twilight: [grabs Cadance and pulls back]
T-850: [grabs Chrysalis' tail, and pulls on her making her let go]
Queen Chrysalis: HEY!!! LET ME GO!!!
T-850: [opens his fuel cell and takes out the ruptured fuel cell and jams it in a main reactor] You are terminated.
[it blows up killing the other villains]
[but then who should Thomas' group meet but]
Tirek: Going somewhere?
Princess Celestia: Tirek.
Tirek: You may of beaten everyone else but you won’t get past me!
Percy: Oh yeah? We’ll see about that.
Brian: Let me borrow this for 5 minutes. [grabs Twi’s Lightsaber]
Twilight: Go ahead.
Brian: [activates it.] I’m getting my Lightsaber back!
Tirek: Come and get it. [activates a crossgaurd Lightsaber]
[And then Brian and Tirek clash sabers at different angles]
[Brian Force leaps back and then charges forward again, and they clash sabers again]
[the 2 then clash sabers with Tirek at several different angles but then Tirek shoots magic at Brian, sending him flying back and then he shoots another at him but blocks it away]
Tirek: You can't beat me, Snoopy. For I have the Purple Diamond! [shows the false one]
Brian: Sorry to tell you this, but that's not the Purple Diamond.
Tirek: Oh yeah? Watch as I will become stronger! [he then warms up his magic sphere above his head, ready to take the diamond's power but nothing happens] What? [he tries again, but still nothing] WHAT?! WHY WON'T THIS WORK!?
Brian: Like I said, that's not the real Purple Diamond, you have a fake one. [he then Force crushes the fake one] Now, you better surrender, or else.
Tirek: [growling] NEVER!!! I won't stop this until you're in your grave! [he then reactivates his Lightsaber]
Brian: I warned you. [he charges forward]
[but then Brian deactivates Twi's Lightsaber and then starts to shoot at Tirek, but Tirek deflects each of the shots with his magic]
[And then Brian and Tirek clash sabers at different angles]
[Brian Force leaps back and then charges forward again, shooting at Tirek and they clash sabers again]
Twilight: I never thought of that. [she then races forward and notices Brian's Lightsaber hanging from Tirek's hip] Time to join in the duel. [she then Force grab Brian's Lightsaber and activates it]
Tirek: [notices Twilight joining in] finally, a fight worthy of my time. [his lightsaber then deploys a second blade!]
[the 2 then clash sabers with Tirek at several different angles but then Tirek shoots magic at Brian, sending him flying back and then he shoots another at Twilight which strikes her!]
Twilight: AAAH!! [falls off the platform, dropping Brian's Lightsaber]
Tirek: [grins evilly]
Brian: That was a terrible mistake you just made.
Tirek: Why? Because you don't have anyone to die before you?
Brian: [Force grabs his own Lightsaber and he activates his and Twilight's Lightsaber] No, because I have nothing left to fear. And now, it's your turn.
[Brian then Force leaps forward and clashes sabers with Tirek]
[they continue clashing sabers as we then view Twilight on the lower platform]
[Camera pans back in the theater, where all of the pirates in the audience weep]
Captain: That's the end of Twilight Sparkle. [To a pirate] Come here, you. [Hugs him tight when a parrot lands on his shoulder]
Captain's Parrot: *squawk* Shut up and look at the screen.
Captain: The bird's right. Look! [Camera goes back to movie to show the teardrop again] It's her royal assistant Spike.
Spike: TWILIGHT!!! [races up to her] Twilight! Are you okay? Twilight! Twilight! Wake up! [smacks her and Twilight start to awaken]
[The pirates and audience cheer]
Spike: Twilight, are you okay? Is Brian okay?
[Twilight then looks up and see Brian is winning in the duel against Tirek]
Twilight: Yeah. Actually, I think he's better than okay.
[Brian continues clashing sabers with Tirek as they approach the edge of the platform]
Tirek: You should not have come back.
Brian: Well, news flash Monkey brained, Centaur, I will allow to return to help my friends no matter what the situation is!
Tirek: Well you’ll never stop me!
Princess Celestia: If you’re so powerful then why don’t you battle us all then? [grabs her Lightsaber and activates it]
Princess Luna: It is time to end this demon once and for all. [activates her Lightsaber]
Cadance: [activates hers]
Shining Armor: Finally, I get to get back at you for what you did to my wife! [activates his Lightsaber]
Sylveon: [Force deploys her Lightsabers and activates them]
Thomas: [deploys his Lightsaber]
Percy: [deploys his own saber and draws his energy axe]
James: Mind if we join in?
[James and Edward walk into view]
Princess Celestia: Gladly.
Thomas: Your reign of terror comes to an end now, Tirek.
Tirek: We will see. Thomas the Junk Engine!
[Thomas and Percy then activates their sabers as Tirek leaps forward and they start clashing sabers as “Anakin Vs. Obi-Wan / Battle of the Heroes” starts playing]
[as they continue clashing sabers, James then Force throws an object at a panel which opens another door to a huge room with lots of platforms and concrete pillars as well as other reactors]
[the battle continues down the platform as they start coming to a big junction in the middle of the room]
Princess Celestia: I’ll show you earth pony strength! [she then leaps up and then kicks Tirek in the face]
Tirek: GAAAH!! [some of his teeth fly out from the kick] (snarls)
[he then clashes Sabers again as he picks up Celestia with his magic and throws her against one of the pillars]
Edward: [cocks his Fusion Shotgun then fires, and the blast sends Tirek flying backward into another pillar]
Princess Luna: Move forward!
[they all slowly walk forward as Tirek then gets back up and starts running for them but Edward fires his Fusion Shotgun at him again, sending him back into the pillar]
[Then out of view, Team Griffin/Eeveelution are watching the scene]
Vaporeon: Man, Tirek's getting his butt kicked out there.
Latios: D'oh, screw it! We can't just sit here powerless!
Jolteon: You know he's actually got a point. I mean, if Tirek ain't Force Sensitive, why is he...
Bardock: Don't you start.
Latias: Hey, we've gone crazy! I mean we've been stabbed and blown up!
Glaceon: We've been stabbed and blown up to. And I've been dumped by the only boyfriend I'd ever had!
Flareon: Same here, But do you know the difference? When my girlfriend left me, she took all my money, when your boyfriend left you, he took all your money.
[Record player scratch plays]
Kida: Gonna need a Senzu Bean for that one.
[they continue slowly moving forward, as Tirek gets back up again and then he leaps forward and clashes Sabers again, and then he fires his magic at them, sending most of the team flying onto other platforms, and then he lifts up Brian and Cadance and starts chocking them as he then starts to make them bring their own sabers to their necks]
[but then, Cera jumps into the scene]
Cera: Oy, Monkey Horse!
[Cera the charges Tirek and slams into him, making him release Briand and Cadance as Cera ignites her Energy sword, and clashes with Tirek's saber as Tirek then tries to deliver a stab but Cera catches the saber in the open middle of her Energy Sword and twists the saber, as Tirek's wrist cracks]
[this action makes Tirek let go of the saber as Cera extinguishes it and throws it away, before she starts throwing punches into Tirek's face as Tirek tries to punch her but she blocks each of his shots before she catches one fist in the mid-swing and punches him in the face with it before she throws some more punches to his face as blood spews from his mouth before she spins and delivers a buck to Tirek's chest, making him fall the ground as Cera then slowly backs up into the shadows]
Tirek: [graons as he slowly gets back up] WHERE ARE YOU?! COME OUT AND FACE ME, GIRL!!
Cera: (Voice only) You Really think you're better than my friends or the Equestian royalty? You're not! You're just a messed up freak!
[Tirek looks all around the place trying to spot Cera but she isn't anywhere to be seen]
Cera: [laughs] (voice only) You should've listened to that one Trooper from the beginning, Tirek. [laughs again] He was right! There was another Centaur around, a real Centaur!
Tirek: WHERE ARE YOU!? AND STOP SAYING THAT!
Cera: (voice only) You can't deny it, Tirek! You're not as strong as you think! You may have strength in muscles and magic, but not brains!
Tirek: [slowly get more angry] SHUT UP!! SHUT UP!!
[then there's a gunshot as a bullet hits Tirek's left leg]
Tirek: Ah! [then one cuts through his left shoulder] AH!!
Cera: (voice only) Surprising you can see when someone is about to charge you, but you can't see a bullet approaching you!
Tirek: ENOUGH OF THIS!! COME OUT ALREADY!! WHERE ARE YOU?!
Cera: [appears from the shadows] Right here.
[When Tirek turns to face her, Cera then throws a punch so hard, Tirek goes flying backwards as he hits a pipe on the ceiling, breaking his left horn off his head, as he falls back to the ground]
[Unfortunately, Tirek lands back near his Saber which he grabs and reactivates it]
[Brian then clashes sabers with him, as the others join back in as they slowly make their way on the platform]
[but then suddenly there's another blast as a blast strike Tirek in the left leg]
Vinny: What the? Who fired that shot?
[then we see the Predator standing a few feet away]
Tirek: A Predator?! [laughs] I would love to see a...
Predator: ROAR!!!! [activates his blade knuckles and slashes Tirek's chest several times]
Tirek: [yells in pain as the Predator slashes him]
Brian: You were right, I was a coward, but now I know there's something stronger than fear. Far stronger, the Force!
Tirek: (snarls and he is ready to clash again)
Brian: Let me show how strong it is! [he destroys Tirek's Lightsaber and does a powerful force blast]
Tirek: [tumbles on some pillars] DIE LIKE YOUR BROTHER!!!!
Brian: He is revived! [Punches him]
Percy: You think you can beat us?! Well, you’re wrong! Because we have something you don’t! [he then jams the head of the energy axe in Tirek’s Left shoulder and then tears it off!]
Brian: [rips off his nose ring]
[then Sylveon Force Leaps towards him]
Sylveon: YAAAAAH!!!! [he then blinds Tirek with her sabers!]
Tirek: [as Muska] AAAAH!!! MY EYES!!! I CAN’T SEE!!!
Princess Luna: Good, now you will not see how you die!
Brian: Yeah, you may of corrupted Celestia, Luna, and Cadance, and tried to kill me, but you won't live to tell the tale of how you lost to Brian Griffin and his friends! Now, you die!
[Brian then delivers a strong Force push, sending Tirek flying back as he spins around, then flies right into the blade of Cera's Energy sword!]
Cera: Gotcha, Monkey Horse. [gives him a peck on his cheek as she thrusts her sword deeper into his chest]
Tirek: [pants heavily before he lets one last breath then slowly he starts to fall to the ground as the sword slides out from his chest, and his body then goes falling from the platform and into the exploding reactor below]
Princess Luna: Finally, the demon is dead.
Cadance: Yeah, but it won’t bring back Twilight.
Twilight: What are you talking about? [she walks up] I’m not going anywhere.
Brian: [hugs her] You’re alive!
Thomas: We thought we lost you.
Twilight: So did I.
[suddenly, a large slab of concrete lands on the platform behind them]
[then there’s another explosion as slabs of concrete start falling from the ceiling]
Percy: Yeow! What’s going on?!
Thomas: Our battle must’ve trigger an explosion from one of the reactors below!
[more slabs of concrete fall]
Ignator: And now the building’s collapsing!
Brian: Let’s get out of here!
[They then race out of the building as bigger slabs of concrete falls and the pillars start collapsing domino style, and they make it out, just in time. As the building then caves in and the whole place collapses in a big cloud of dust.]
[The dust then clears and there’s nothing left of the building but a pile of rubble]
Vinny: Man, that was way too close!
Thomas: Well, even if the villains survived, they won’t be getting out of there anytime.
Sylveon: Alright. Now, let’s go save Anna.
[Then we see Galvatrain standing on a hill watching the whole thing]
Galvatrain: We shall meet again, OpThomas. For I am reborn.