The final battle began as standing on a platform very close to the rip was Ash and Goh, along with their Pokémon Pikachu, Lucario, and Cinderace. In front of them was the ancient evil, the Mawgu, who planned to conquer the world, while also destroying the Pokémon world in the process, unless Ash and his friends stop him by pushing closer to the rip, so when the Ultra-Rip-Zipper was activated, it will trap the Mawgu inside.
Ash: Come out! Gengar! Dragonite! Sirfetch'd! Dracovish!
Ash called out the rest of his team, and along with Pikachu and Lucario, they were ready, and so were Goh and Cinderace.
Ash: Lucario, use Aura Sphere! Gengar, Shadow Ball!
Goh: Cinderace, use Pyro Ball!
Both Lucario and Gengar fired a sphere of aura and shadow while Cinderace kicked a ball of fire. The Mawgu dodged the two attacks while he swiped away the Pyro Ball with his arm until he was faced with Dragonite.
Ash: Dragonite, use Hyper Beam!
The Dragon Pokémon unleashed the powerful beam of energy at the Mawgu and exploded. But then the Mawgu came out of the smoke and threw a glob of ooze at the others.
Goh: Look out!
Everyone dodged the glob of ooze in time, but then they saw the Mawgu coming at them with his fists raised. Sirfetch'd, like the Knight he is, stood in the Mawgu's way to protect his friends.
Ash: Use Detect!
The Mawgu's fists landed on Sirfetch'd, but thanks to Detect the Pokémon dodged it in time as he landed on his fist.
Ash: Now use Night Slash!
Sirfetch'd ran on the Mawgu's arm as he's going to attack his face, but the ancient evil had a nasty surprise as he spit a stream of ooze right when Sirfetch'd got close enough for the strike.
Ash: SIRFETCH'D
Everyone was shocked as Sirfetch'd landed on the ground. Ash ran to him to check on his Pokémon.
Ash: Sirfetch'd, are you alright?
To his horror, Ash noticed purple rashes forming on Sirfetch'd body.
Goh: He's infected by the ooze!
Everyone was horrified by this as the Mawgu laughed.
Mawgu: HAHAHAHAHAHA! Soon your friend will turn against you and follow me instead!
Sirfetch'd: Sirfetch'd!
The Mawgu and the others became surprised as Sirfetch'd stood back up as he glared at the ancient evil.
Ash: Sirfetch'd?
Still glaring at the Mawgu, he pointed his lick at him, showing that he's not going to submit to him.
Mawgu: Really? How long do you think you'll be able to keep your sense of self? (Laughs evilly).
The others became angry at this as the Mawgu laughed… until Dracovish bit on his head.
Mawgu: Huh?
Dracovish was upset at what this bad guy did to his friend, so using Ice Fang he started to cover his head in ice.
Mawgu: GAH! GET OFF ME!
The Mawgu began to trash around in order to throw Dracovish off. Meanwhile, Sirfetch'd still has his leek pointed at the Mawgu, until he started to gather orange energy around him and at the tip of his leek.
Ash: Huh? What's going on?
The Mawgu then threw Dracovish of his head, but then the hybrid Fossil Pokémon stopped in mid-air as he was covered in a blue aura.
Goh: Dracovish too?!
Both Dracovish and Sirfetch'd charged in at the Mawgu, with the Fossil Pokemon's aura turning into a Draconic form while Sirfetch'd turned into an orange comet. Both attacks hit the Mawgu hard.
Mawgu: GRAAAAAH!
Ash was surprised at this while Goh recognized those moves.
Goh: Dracovish just learned Dragon Rush! And I think Sirfetch'd used Meteor Assault!
Ash then snapped out of his surprise once he saw the Mawgu was being pushed closer to the rip, and he was a little dazed from the attack.
Ash: Now's our chance! Let's push the Mawgu back with everything we've got!
Now all the Pokémon began their final attack at the Mawgu. Lucario jumped and used Force Palm on the Mawgu's chest right when he recovered. Dragone did a Dragon Claw Uppercut on the Mawgu's chin. Gengar grabbed the dazed Mawgu with Psychic and started spinning him around, making him dizzy. Then Pikachu and Cinderace jumped together and delivered an Iron Tail and Blaze Kick on the face, sending the Mawgu flying towards the rip.
Goh: We did it!
The Mawgu was just about to fall into the rip… until he stopped himself just in time as he glared at them, much to their shock. The Mawgu then created a huge blob of Ooze and threw it at them!
Goh: Oh no!
Ash and Goh didn't know what to do as the attack came too fast, until all the Pokémon huddled together and shielded them right when the attack hit.
The attack made a loud explosion that can be seen by Serena and the others.
Serena: Oh no, Ash!
The smoke cleared to reveal Ash and Goh laying on the floor. But they were uninjured as they started to get back up.
Ash: Are you alright, Goh?
Goh: Yeah… What about our Pokémon?
But when he looked he gasped at what he saw; Cinderace was on the floor with purple rashes on his body.
Goh: Cinderace!
Ash was horrified to see that all of his Pokémon were in the same state as Cinderace.
Ash: Pikachu! Lucario! Gengar! Dragonite! Sirfetch'd! Dracovish!
All of them got infected from the Mawgu's Ooze when they protected their Trainers from the attack.
Mawgu: (Evil Laugh)...
Ash and Goh heard the Mawgu laughing as he descended towards them.
Mawgu: How noble for you Pokémon to protect you! However, they are now infected by my ooze! Hahahaha!
Ash was angry as he went and scooped Pikachu in his arms. So did Goh with Cinderace.
Ash: Pikachu! Wake up, buddy!
Goh: Cinderace, say something!
Suddenly, Pikachu's ears twitched which brought relief to Ash. But then he became confused when Pikachu jumped away and started growling at him.
Ash: Pikachu?
Cinderace shoved Goh away as the boy looked at his Pokémon in shock.
Goh: Cinderace?!
All of Ash's other Pokémon got up and glared at them.
Ash: What's wrong with you guys?!
Mawgu: Don't you realize by now? They're my Pokémon now! Hahahaha!
Ash and Goh grunted as they remembered that the Mawgu's Ooze turns anyone into his slaves. Ash and Goh got up and backed away as their infected Pokémon approached them.
Mawgu: What will you do now, Chosen Ones? Without your Pokémon, you can no longer stop me! I've told you already! I chose your DESTRUCTION!
Goh sweated as his other two Pokémon couldn't help them against such strong Pokémon. He doesn't know what to do. However…
Ash: No way, Mawgu!
Goh and the Mawgu were surprised at this as Ash held his stance.
Ash: I'm not giving up so easily!
Ash then started to remember all the challenges he and Pikachu faced in the Pokémon Leagues of each Region, including their interactions with Legendary Pokémon and saving the world.
Ash: Me and Pokémon, we overcame many challenges during our adventures, and we certainly wouldn't give up because of your ooze! Me and my Pokémon, we will win this!
Goh was awed at Ash's speech, even the Pokémon stopped advancing as Ash's words reached them. Suddenly, something glowed in Ash's pocket.
Ash: Huh?
Mawgu: What is that light?!
Ash knew what it was as he took it out. Raising his hand showed that he was now wearing his Z-Ring, and the light that's coming is the Pikashium-Z.
Goh: Ash's Z-Ring! He had it this whole time!
The Z-Ring then started to shine so bright the Mawgu had to look away.
Mawgu: So bright! What is that thing?!
Suddenly, something incredible happened. All the purple rashes on the Pokémon started to disappear, meaning the Pokémon are being freed.
Goh: The rashes are vanishing! Ash's Z-Ring is curing them!
The Mawgu couldn't believe what he was hearing.
Mawgu: Imposible!
Ash: Now! This time we will defeat you Mawgu! Let 's go Pikachu!
Pikachu: Pika!
Ash threw his hat off which Pikachu grabbed and put it on his head. Ash then activated the power of his Z-Ring as he crossed his arms into an X.
Mawgu: I wouldn't let you!
Before the Mawgu could stop him, he was hit by all the other Pokémon.
Ash and Pikachu fistbumped before they did a slap with Pikachu's tail and Ash's hand. Ash then transferred his Z-Power to Pikachu as the Mouse Pokémon felt his friend's power.
Ash: Much bigger than a Thunderbolt! 10,000,000 Volt Thunderbolt!
Pikachu was feeling the power as his hair was standing.
Ash: Yeah! This is much, much bigger! At super full power!
Pikachu: Pikapika!
Pikachu was ready to unleash it.
Ash: Pikachu, use 10,000,000 Volt Thunderbolt!
A storm cloud appeared above the skies and Pikachu jumped into the air. Multiple lightning bolts rained down and were absorbed into Pikachu's body as he was surrounded in an aura of electricity. He then unleashed seven bolts of lightning, each holding the color of the rainbow.
Mawgu: You wouldn't defeat me!
The Mawgu then hurled another huge blob of Ooze at the attack, but the Z-Move overpowered it as it went right through it.
Mawgu: WHAT?!
The attack then hit the Mawgu and pushed him all the way through the rip as he screamed.
Mawgu: AAAAAAAAAAAAAAAAAAAAAHH!
Goh: You guys did! Ash, Pikachu, that was incredible!
Ash and Pikachu were exhausted, but knew there wasn't time to relax just yet.
Ash: It's not over yet!
Ash then ran towards the edge. At that moment the Mawgu was pulling himself out of the rip and he was furious!
Ash: Sophocles! Now!
Sophocles, hearing his signal, activated the Ultra-Rip-Zipper, which sends a beam that hits the rip. Just when the Mawgu fully came out of the rip, he was suddenly being pulled back in!
Mawgu: What's happening?!
Ash: We're closing the rip, Mawgu! Along with you in it!
The Mawgu realized that the Chosen Ones planned to imprison him behind the rip. He glared at the Ash and Goh one last time before being pulled in.
Mawgu: This isn't over, Chosen Ones! Hahahahahaha!
And with that, he was pulled inside the rip as it closed.
Ash and Goh remained on guard, waiting for any unexpected surprise, until realizing that they actually won.
Goh: We did it… we won!
Ash and Goh, along with their Pokémon, jumped in the air in joy. Serena and the others rejoice as they were glad that they managed to seal the Mawgu away. Ash and Goh high fived at their victory, until… a blue rip suddenly opened!
Goh: What the?!
They suddenly felt a strong pull as all the debris was being sucked into the new rip!
Goh: What's going on?!
Ash's Ultra Communicator then turned on as the screen appeared with Rotom on it.
Rotom: Ash! A new rip has appeared and it's sucking all the energy and debris the Mawgu has taken back to our world! You guys better leave cause I don't think it will be safe with all the debris in the way!
Ash turned to Goh as they both nodded. They all returned their Pokémon except Dragonite and Gengar. Ash, Goh and Pikachu were riding on Dragonite while Gengar followed. They found Serena and the others as they were riding their own Pokémon. Serena and Iris on her Dragonite, Dawn on Togekiss, and Team Rocket on Garchomp and Pelipper too as he held on Garchomp's tail.
Serena: Where's Clemont and Sophocles?!
Ash: I sent Gengar to pick them up!
Right on cue, Gengar came while holding a screaming Clemont and Sophocles.
Ash: Let's get out of here!
The others agreed as they flew out of the storm. All over Volcano Island, all the stuff that fell on the island is being pulled back into the rift. The Hermit Crabs, Exiled Crabs, the Myrmec Tribe, and the Florians watched all this happen as all the stuff was being pulled into the storm. Once everything entered the storm itself was starting to be sucked up inside until it vanished completely. Everyone on Volcano Island cheered as they knew that this means that the Mawgu has been defeated, and they have the Chosen Ones to thank for.
Ash and his friends stood at the beach of Camp Castaway. Now that the Mawgu has been defeated and sealed away, it's time for them to go back home.
Rotom: Okay everyone, Burnet is activating the portal now! Time to go home!
Ash and the others turned to the Wise Old Crab and the Myrmec Queen, who came to see them off.
Wise Old Crab: You see, Pokémon Catcher? You saved us all, exactly as foretold in legend.
Goh: Wow! It's like you knew what was going to happen all along!
At that moment, an Ultra Wormhole appeared in front of them, and they knew that this was the path back home.
Myrmec Queen: Farewell, Chosen Ones, and thank you. You are truly heroes.
May became bashful at that.
May: Awww. It was nothing.
Ash: Goodbye, Shelly! I'm glad we could help!
With everyone saying their goodbyes, they all turned to the gate that will guide them home and walked through it one by one.
Jessie: We're finally going back home!
James: And once we'll get there we'll get something delicious to eat!
Meowth: Yeah, then we can resume our mission to capture Pikachu again!
Wobbuffet: Woooobbuffet!
Iris: I'm really gonna miss this place.
May: Who knows, Iris. Maybe we'll come back one day.
Dawn: Yeah! There's no need to worry! We may come here for a vacation.
Goh: I'm glad I'm going back home… I really need a shower.
Serena and Ash were the last ones.
Serena: I still can't believe they thought we were their Chosen Ones.
Ash: I don't know, Serena. From what I know, legends can sometimes surprise you.
And with that, they entered the Ultra Wormhole as it closed behind them.
What Ash and his friends didn't know was that on the other side of the cliff were large ancient statues depicting them and their Pokémon. Seems Ash was right about the legends surprising them.