With Team Rocket
After Neo Team Plasma's withdrawal, Jessie and James realised that something had been left behind by one of the Neo Plasma Grunts.
'What's this?" Jessie asked, and she grabbed it.
"What is it?" Jessie asked, to which James replied "I think it's some kind of communicator. This could come in very handy"
"True, let's send a report back to the boss," Meowth said, to which both Jessie and James nodded, and they snuck out of Opelucid City, James pocketing the communicator as they did so.

When they reached a hiding spot, they open the communicator with Giovanni.
"How goes the operation with Neo Team Plasma?" Giovanni asked, to which Jessie replied "We, don't know if Neo Team Plasma succeeded in whatever their goals were in Opelucid City, but we did defeat a few Grunts. Apparently, they were going after something called the DNA Splicers?"
"Never heard of them. Well, this makes things more complicated. There doesn't seem to be much we can do anymore. You're free for now, thanks for this information, we'll get our best Rockets onto the case to find out what's going on" Giovanni replied, to which Jessie and James nod. The communication was then cut,
"You know James, I'm not feeling so hot about this whole Team Rocket thing," Jessie said suddenly, almost as soon as the communication was cut. James looked to her and said "You know, I kinda agree. It feels like we've had the same mission since day one, and it feels, monotonous"
"We're trying to counter Neo Team Plasma. It's as simple as that" Jessie replied, to which James responded, "What does it matter when they completed their mission successfully anyway?"
"We'll have to trust the boss' instincts on this and continue fighting them. But I get the sentiment James, this is really getting us nowhere" Jessie responded, to which James nodded.
"Well, we'd better find out where those Plasma Scumbags are headed, so we can continue opposing them," Meowth said, to which Jessie and James nod, said "Good idea Meowth" and they departed.

Meanwhile, in Opelucid City itself. though seven members of Neo Team Plasma were captured, they got the other DNA Splicers. As they depart, Ash said, "What do they want with the splicers?"
"I don't know. But, we have to follow them to find out what they're planning with them" Drayden replied. Then, he got a call.
"Who is this?" Drayden asked as he took the call. Marlon was on the other side, and he responded "Yo dude, it's getting pretty cold up here in Humilau City. Do you know anything about why?"
"Sounds like Neo Team Plasma's nearby" Drayden replied, to which Marlon nodded, then said "Alright, I'll keep an eye out for them. Also, got any trainers looking for their final badges?"
"Yes," Drayden responded, to which Marlon nodded, then added "Send them this way. The Unova League isn't far away, and I'd like to test them, see if they're ready for the Tournament"
"Alright. Drayden out" Drayden replied, and the communication was cut.

"So what's going on?" Ash asked, to which Drayden replied "It looks like Neo Team Plasma are headed for Humilau City. You can head back to Undella Town, and take the Marine Tube through to Humilau City. Marlon will be waiting for you there"
"Humilau City, alright" Ash replied. Hilda nodded, then added "It's gonna take a while to get back though"
"Not if you use the train to get back. There's one that loops around from Nimbasa City, and two of its stops are Opelucid City and Undella Town. I'll show you the way to the station" Drayden said, to which Ash and Hilda both responded "Cool, lead the way" and they headed off towards the station.

Meanwhile, Team Rocket has overheard the conversation, and James said "If we want to oppose Neo Team Plasma, seems like Humilau City is our best bet"
"Alright. Since we have no other orders, that's what we'll do I guess" Jessie responded, and Meowth said "We need to cross the Marine Tube. We're gonna have to disguise to avoid drawing attention to ourselves"
"That can be handled" Jessie responded, and after a brief session of brainstorming, they agree on a plan and depart.

When they arrive at the train station, Ash and Hilda get tickets for the next train that'll take them to Undella Town.
"Thanks for the help, shame about the DNA Splicers, but we'll do our best to get them back," Ash said, to which Drayden nodded, and replied "I wish you good luck on that mission, see you later"
"See you Drayden" Hilda responded as she and Ash get on the train, and it departs.

As they pulled out of Opelucid City, Hilda said, enthusiastically, to Ash "Drayden's so cool! I had heard of his coolness from my big bro, but he's even cooler than big bro described"
"I have to admit, he's a cool guy. No surprise he got the position he did" Ash replied, and Pikachu called in agreement.
"So, what do you know about the Marine Tube?" Ash asked, to which Hilda replied by shrugging, and said "No idea, sorry"
"Alright, guess that'll be a new experience for both of us then" Ash replied, smiling, which Hilda returned, still vibrating with excitement over having met Drayden.

While they travel, they start hearing a gentle song.
"Who, or what is singing that tune?" Ash asked, enjoying the music, to which Hilda replied: "Not sure".
As it turned out, Meloetta was singing into the intercom. How did she get in there? The invisibility of course.
Team Rocket, who had managed to sneak aboard the same train, was also enchanted by the music.
"Do you think we could capture whoever is singing that song for the boss?" Jessie asked, to which Meowth replied "We can try that. Imagine", and a Meowth vision started.

"Imagine the boss is at his desk and is listening to terrible music," Meowth said, and Giovanni said, annoyed at the music "I can't concentrate with all of this shitty music"
Then, a Meloetta appears and starts singing. Meowth, as the vision continued, said "And imagine Meloetta arrives and starts singing, and Giovanni is able to get his work done double-time", then the Giovanni in Meowth's vision said "This Meloetta has enchanted my life. I should give Jessie, James and Meowth big rewards", and the vision ended.

"Sounds like a plan. Now, where would the intercom be stationed at?" James asked, but before they figured out where the music came from, Meloetta finished singing, and, still invisible, floated out again to find a place to curl up to rest.

"That was a lovely song," Ash said, to which Hilda replied, "Agreed. That sounded like the Mythical Pokémon Meloetta. A lot of modern music in Unova is derived from her songs".
"Cool," Ash responded, smiling. The conductor then came over the intercom and said "Two things. Firstly, we will be in Undella Town in ten minutes. And second, whoever used the microphone to sing, you're not allowed in this area, but I will forgive it for the amazing music you provided".

In the compartment near the back, Meloetta, hearing this, smiled at being complimented.

Back in Team Rocket's compartment, Jessie said "Well, this is it, our stop", to which both James and Meowth nodded.

Back with Ash and Hilda, they got ready to depart the train. Ash looked around, and he briefly thought, as they departed the train, he saw a humanoid figure with long, green and blue hair, large eyes, wearing a black dress, black headphones with a microphone, and quarter-note arms. However, the figure was gone next second.
"So, where's the entrance to the Marine Tube?" Hilda asked, to which Ash responded "We should ask around, see if anyone knows"
"Sounds like a plan" Hilda responded, and they started asking around.

Hilda had no luck asking around for where the Marine Tube was. Ash, on the other hand, did.

The fourth person Ash asked, said "I can take you to the Marine Tube, but you'll have to defeat my Starmie before I show you" the Swimmer said, to which Ash responded, "That's fine by me". As the battle started, Hilda arrived to watch.
"Alright Starmie, let's do this," the Swimmer said and Starmie materialised. Ash nodded, then added "Now Jellicent, I choose you" and Jellicent materialised.

Battle: Starmie VS Jellicent
"Starmie, use Thunderbolt" the Swimmer commanded, and Starmie unleashed a blast of electricity at Jellicent, but Ash was ready.
"Jellicent, combine Ominous Wind with spinning to deflect it" Ash called, and Jellicent started spinning while blowing a spectral wind, which deflected the Thunderbolt.
"Starmie, dodge the Ominous Wind and use another Thunderbolt" the Swimmer responded, and Starmie avoided the spinning Ominous Wind, then unleashed another blast of electricity at Jellicent, dealing Minor damage.
"Quick Jellicent, respond with Giga Drain" Ash commanded, and Jellicent unleashed multiple tentacles of natural energy at Starmie, dealing Moderate damage, restoring a Minor amount of health.
"We can still win! Starmie, use Thunderbolt" the Swimmer called, and Starmie unleashed a blast of electricity at Jellicent, but Ash was ready again.
"Jellicent, fire a Water Pulse into the ground, dodge it, then use Shadow Ball" Ash commanded, and Jellicent shot a ball of water into the ground, which helped deflect the Thunderbolt. Then, Jellicent fired a ball of spectral energy at Starmie, inflicting Significant damage.
"Starmie, use Thunderbolt again" the Swimmer called, and this time Starmie's aim was true, the blast of electricity dealing Minor damage to Jellicent.
"You OK Jellicent?" Ash asked, to which Jellicent nodded. Ash smiled, then said "Good to hear. Now end this, Giga Drain" and Jellicent shot several natural tentacles at Starmie, KO'ing it and healing a Slight amount of health.
"Aw man, I lost. Oh well, I'll guide you to the Marine Tube. It only opened very recently, so not a lot of people know about it" the Swimmer said as Starmie was withdrawn.
Conclusion: Jellicent wins

"Well done Ash, seems your Jellicent has learned to utilise Counter Shield with both Water Pulse and Ominous Wind," Hilda said, smiling, to which Ash and the Swimmer both turned to face her, and the former smiled and responded with "Yeah, Jellicent's really getting the Counter Shield down. I'm very proud" and Jellicent cheered. The Swimmer then turned back to Ash, and asked: "Is she your girlfriend?"
"No, she's a close friend, but that's it" Ash replied, to which Hilda nodded.
"Alright then, what's your name?" the Swimmer asked, to which Hilda replied, "I'm Hilda, who are you?"
"Samuel" Samuel replied, nodding. He then added "Now, Ash, Hilda, follow me" and he headed towards the Marine Tube, with Ash and Hilda close behind.

When they arrived, the receptionist said "The Marine Tube is ahead! Please enjoy the stunning scenery!"
"We intend to" both Ash and Hilda responded at the same time. Samuel then said "I hope you enjoy this passage, it truly is wondrous", to which both Ash and Hilda replied "We hope so", and they entered the Marine Tube.

As they went down into the ocean, Ash asked "Wait, are we underwater?", to which a Janitor, standing nearby, said "Yep. The Marine Tube is an Undersea Tunnel, so to speak. Do you know how such tunnels are made?"
"No, this is something special. How is something incredible like this made?" Hilda asked, to which the Janitor responded "It's quite simple! They're built on land, and then sunk into the sea! Without Pokémon, the construction would've been impossible"
"Incredible" Hilda replied, and Ash asked "How did you avoid getting water in? Did you seal the ends beforehand? Or did you pump any water that got in, out?", to which the Janitor responded "Sealed at both ends before being submerged"
"Cool," both Ash and Hilda responded before they headed in. As they did, the Janitor called "Enjoy the scenery".

Both Ash and Hilda are enamoured as soon as they enter.
"Oh, I have an amazing idea. It's the first time any member of my family has been here, so I want to film my journey through here, as it's such a wondrous place" Hilda said, to which Ash responded "Go ahead, we can show this to my mom, and the Professor's too"
"Sounds like a plan" Hilda responded, and she got out her tablet, and set up the recording.
"Let's go," Ash said, and like him and Hilda step across the Marine Tube, Hilda documents as much as possible.
"Is it just me? Or are those lights in the water?" Ash asked, to which a Black Belt, who's also enjoying the scenery, said "The lights are designed so the Pokémon isn't affected by the lights, but we can see the surrounding ocean"
"Awesome" Ash responded. Hilda then looked around and said "We're on the seafloor. How cool is this?"
"Very cool" Ash replied, as he looked around, seeing Basculin, Frillish, Wailord, and numerous other Water-type Pokémon. As they get half-way, the seafloor falls away to reveal a trench.
"Wow! It's an ocean trench! So deep! Maybe six miles deep?" one guy said, while his, Ash assumed partner, added "That's right, it's deep. Love is infinitely deep"
"That's deep" Hilda responded, to which Ash added "In more ways than one. Now, we'd better get going, we've got a city to reach", to which Hilda nodded, still in wonder, and they continued through the tube.
"This truly is a technological wonder. How the hell did they get the lights down?" Hilda asked, to which Ash replied "Scuba divers, that's the only thing I could think of. Also, I assume electrical work underground had to take place"
"That'd make sense" Hilda responded.
As they reach the exit of the Marine Tube, Ash overheard someone say "This place is like a walk-through aquarium, but isn't this a place for Pokémon to see us?"
"I wonder what they'd say, seeing us in this tube" Hilda replied, to which Ash responded "If I understood my Jellicent, we'd have an idea of that"
"True," Hilda said, who was still taking in every part of the Marine Tube with her tablet.
"This is truly an incredible piece of technology," Ash said as they departed the Marine Tube.

As they exit the Marine Tube, they hear an old man say to a group of young children "The path is to see rather than to move". Ash then spotted a large sign, which explained the Marine Tube.
"How Hilda, make sure you get a big shot of this" Ash said, pointing to the sign. Hilda nodded, and pointed her tablet to the sign, and took a photo. The information read "The Marine Tube is an undersea tunnel, built to commemorate the friendship between Undella Town and Humilau City"
"I didn't know that the two places were so close. I had only heard of Humilau City, but there didn't seem to be an easy way to get there" Hilda said. She then continued reading, which said "It is made of hardened glass 9.8 inches thick, which can withstand high water pressure and contact with huge Pokémon. The Marine Tube was built using the best technology in Unova. Please walk through and contemplate the underwater scenery"
"How long did this take to make I wonder?" Ash asked, and, after a bit more looking, saw that it took two years to create.
"So, construction on the Marine Tube started around the time your brother went on his journey," Ash said, to which Hilda nodded.
"Hey guys, welcome to Humilau City" came a voice from behind. Turning around, Ash and Hilda see a tanned young make with blue eyes, dark blue hair, wearing blue goggles around his neck, and blue-and-white pants, with dark blue sandals.
"Hello, I'm Ash, and this is my friend and mentee Hilda. Who are you?" Ash asked as he approached the stranger, who responded "I'm Marlon, nice to meet you, you two must be the trainers Drayden told me about"
"Yep, that'd be us" Ash responded, to which Marlon nodded.
"Well, since it's getting pretty late in the day, I recommend you two take some time to explore Humilau Town, then, tomorrow, you can challenge me to a Gym Battle. I believe it'll be for your last badge Hilda" Marlon said, to which she nodded to confirm. Ash then added "My seventh Gym Badge, apparently I'm taking on Drayden for the final badge, in a 6-on-6 battle"
"Cool, good luck with that" Marlon replied. He then headed out, and as he did so, said "I hope you enjoy your stay at Humilau City", to which both Ash and Hilda responded "Thanks", and they followed, a bit behind.

Ash and Hilda arrived at Humilau Town, and Marlon gave them a tour of the city.
"This reminds me of Pacifidlog Town in the Hoenn region, they both have buildings floating in the waves like this" Ash said, to which Hilda responded "I forget sometimes that you have been to other regions"
"Other regions? Sounds cool. I'd love to travel to these other regions someday. For example, I don't remember the name Ash Ketchum, where are you from?" Marlon asked, to which Ash replied "I'm from Pallet Town in the Kanto region"
"There's another region I'd like to visit someday," Marlon said, almost wistfully. Ash smiled, then said "I'm sure you could pay a visit, if Skyla's been there before, she'll know the way"
"Oh yeah, I should ask her" Marlon replied.

When the tour is finished, Ash and Hilda head back to the Pokémon Centre.
"So this is Humilau City, quite a nice place. I'll be sure to send the tour of the Marine Tube through to my family, then I'll head to bed" Hilda said, to which Ash responded "Yeah, as I said, it reminds me of a couple of cities in regions I've travelled through in the past"
"I'd be curious to see this place you've mentioned someday" Hilda responded, to which Ash smiled, and added "I'm sure you will, at some point. Anyway, I'd better get to bed, good night Hilda" Ash said, to which Hilda replied "Good Night Ash". And after Ash gave his Pokémon to Nurse Joy, he headed off. After a few minutes, Hilda did the same with her Pokémon, then followed Ash to her room.