Ash asked for an outdoors gym battle, which Maylene was glad to provide, then they decided between them on having two Pokémon.

"And… obviously you've beaten the Battle Frontier, and you won the Hoenn League," Maylene said, half to herself. "So I should give you the best challenge I can, but it doesn't matter much if I don't win."

"I'll keep an eye on what happens," Cynthia volunteered. "That way you can be sure, hopefully."

"Thanks," Maylene smiled. "That's going to help out a lot…"

She considered. "Hmm. All right, I think I know who I'm using… Reggie, do you want to handle the referee side of things?"

"Sure," Reggie agreed, stepping back. "Two Pokémon a side, obviously… since we're outside there's no hard limits on leaving the arena, but I'll give a fifteen second warning if a Pokémon is abusing that."

"Got it," Ash nodded, concentrating, and two Pokéballs floated next to him. He looked between them, then put one back in his saddle bags. "Okay, ready!"

Maylene held up a Pokéball as well, then sent out a Machoke.

"Hoh!" she said, bowing, as Ash sent out Swampert in response. "I see! This is going to be a battle of brawn!"

"Eh, could be," Swampert said. "Could be there's more of a focus on tactics. We'll see how it plays out."

"Quite!" Machoke agreed.

"Okay, Swampert," Ash said. "Ready?"

Swampert gave a big thumbs-up.

"Begin!" Reggie called.

"Dynamic Punch!" Maylene called, and Machoke lunged forwards. She lashed out at Swampert, knocking him into the air with a punch that came with a sizeable explosion, and Swampert did a half-cartwheel in mid-air.

"Dig!" Ash instructed, and Swampert used Dig as he landed. That meant he went into the ground with a crunch instead of just hitting hard, but his sheer size now meant that he left a big hole instead of a small one, and Maylene pointed.

"Close in and use Brick Break!" she told her Machoke.

"Turn around!" Ash responded. "Muddy Water!"

Machoke's attempt at a close-quarters attack got met by a flood of water coming the other way out of the hole Swampert had dug himself, and her raised arms started out ready to attack but quickly turned into her using them as a shield against the Water-type attack that sent muddy water spattering all over the place.

"Machoke, back!" Maylene said, thinking. "Hmm… how deep is Swampert?"

She closed her eyes, concentrating for a moment, then flung up one arm herself. "Ack!"

"What is it?" Reggie asked. "Is something wrong? Pause the battle!"

Machoke stopped obediently, and so did Swampert – putting down a Mud Shot he'd been about to fire out of the hole.

"Lucario?" Maylene said. "Look carefully at Ash with Aura Sight. Do you see what I see?"

Her Lucario closed his eyes, focusing.

Then nearly fell over.

"Ow," he said, blinking. "My eyes hurt."

"That happens," Cynthia's Lucario told them both. "I don't use Aura Sight at the moment unless I'm sure which way Ash is and I'm not looking in that direction. I'm impressed that it was Maylene who first saw it, though."

"Is that going to be a problem?" Ash asked. "I'd offer to turn it down but I don't actually know how to… I think it's just part of, uh, who I am?"

"It probably is," Cynthia said. "Though I imagine we'll find out the details in future."

"Right," Maylene frowned. "Uh… right, I'll just assume Swampert isn't very far down the hole, I guess… Reggie?"

"Resume in five!" Reggie said, giving them a countdown, and as soon as he reached zero Ash pointed.

"Rock Throw!" he said.

"Brick Break!" Maylene countered, and Machoke smashed the rock to pieces.

Several minutes later, both Pokémon were panting from exertion.

Swampert had come back out of his defensive bunker after Machoke turned out to know Bulk Up, and Ash had decided it was a bad thing to let her build up her strength to that level uninterrupted. Then she'd demonstrated that she also knew Seismic Toss, slamming Swampert into the ground hard, but Swampert had retaliated with an Avalanche that coated Machoke with ice until she flexed and broke her way out of it.

Then it had been back-and-forth, strength against strength, and as the two Pokémon took a breather Ash tried to think about how he could get an advantage.

"...hmm," he said. "Wait, that might work…"

"Look out, Machoke," Maylene warned. "It sounds like he's up to something."

"Dig!" Ash said. "But don't go far down."

"Bulk Up," Maylene called promptly. "Then get ready to respond to what he does!"

Swampert went crunch into the ground, and Ash struck the earth next to him with his hoof.

"Stop there!" he said. "Now – use the strongest Muddy Water you can, into the ground!"

"Into the ground?" Maylene repeated, confused. "What…?"

Swampert's strongest Muddy Water was very strong, after spending so much time training under Koraidon's artificial sunlight, and he might not have known what Ash was getting at but he did it anyway. The Muddy Water attack sent mud fountaining everywhere, prompting Latias to quickly use Safeguard to avoid getting splattered, and Ash waited a long moment to make sure there was enough water.

"Now – Bulldoze!" he said, and Swampert vaulted out of his hole before charging forwards.

"Now I get it," he said, making the ground shake as he advanced.

"Focus Punch!" Maylene ordered, and Machoke shifted her stance a little. She was ready to attack as soon as Swampert got close enough…

...at least, until the ground gave way under her feet, and she slipped.

The central part of the clearing had liquefied slightly, and Machoke's careful stance collapsed as she tried not to fall over completely.

"Hammer Arm!" Ash ordered.

Swampert used Hammer Arm.

Machoke did not get much consolation from how it was not technically Super Effective.

"So, what did you think about that battle?" Cynthia asked, once Reggie had confirmed that Machoke had been knocked out.

"I think-" Maylene began, then stopped and frowned.

"I think…" she reiterated, after thinking about it for a while longer. "That Swampert is recently evolved. He was handling being a Swampert okay, but there were times when what he was doing, and what Ash was ordering, were both sort of… assuming that he was smaller."

She shrugged. "But apart from that, I can't really think of anything? It was a hard-fought battle, and that trick at the end was clever, but nothing really stood out… I can go into a lot more detail, I guess, but during the battle I was mostly just reacting."

"That's all right," Cynthia told her. "I was curious about your opinion of it – don't think your answer was wrong, because for a question like that there isn't really a wrong answer."

She paused. "Except thinking that you didn't do well, that is."

"Gym Leader, get ready to send out your next Pokémon," Reggie said.

"That's you, Lucario," Maylene decided. "Swampert's got to be tired, so let's go!"

Lucario stepped forwards, paws already glowing, and Reggie nodded. "Begin!"

"Mud Bomb!" Ash called.

"Dodge!" Maylene said quickly.

Lucario dodged to the side, doing a handspring on the ground as part of a cartwheel sideways, then Maylene called for an Aura Sphere and her Fighting-type threw one as he got back upright.

Swampert turned, lashing out with a Hammer Arm, and Lucario jumped backwards this time.

"Keep moving around him!" Maylene told Lucario. "He's having trouble turning – and watch out for the muddy bits of the ground!"

Swampert blocked the next Aura Sphere attack, sliding backwards a little on the ground, then before he'd properly recovered Maylene called for Lucario to charge in and use Force Palm.

"Look out, Swampert!" Ash called. "The hole's behind you!"

Swampert tried to move forwards, but Lucario's Force Palm hit him harder than he could compensate for.

"Dang," the Water-type said, then the ground under him collapsed into the hole from his earlier Dig.

"I… think he's out," Ash decided, after several seconds had gone past and Swampert hadn't returned to the battle. "I guess that means I'm moving on to my second Pokémon."

"This should be interesting," Pikachu said.

"Yeah," Ash agreed, taking out both Pokéballs – one to return Swampert, the other to send out his other Pokémon. "Good luck, Buneary!"

He sent the Normal-type out with a flash, and the Rabbit Pokémon did a flip before landing.

His paws went splat on the ground, and he made a face before shaking his head. "Should have expected this with Swampert going first."

"Hmm," Maylene's Lucario said, taking a stance. "I'm sure there's a reason for your trainer to send you out, so I won't underestimate you."

"How does the ground feel, Buneary?" Ash asked.

"Not great, really," Buneary replied. "It's tacky and it's going to make it harder for me to jump."

"Begin!" Reggie said.

"Bounce!" Ash called. "And Ice Beam the ground!"

Buneary's first jump didn't get very high, but his attack promptly froze the ground over with a thin crust of ice. Lucario's greater weight simply crunched through it, and when Buneary landed it fractured into lots of different bits, but it gave him steadier footing.

"Interesting!" Maylene said. "Lucario, Bone Rush!"

Lucario conjured a Bone Rush staff, then Ash called for another Bounce and Buneary sprang in on the attack.

"Dizzy Punch the staff!" Ash added, as Lucario swung it to knock the Normal-type out of the air, and the combination of impacts knocked Buneary away but also knocked him much higher than before.

"Check your aim," Ash warned, watching as Buneary rose into the air. "And – High Jump Kick!"

"Get out of the way!" Maylene called.

Buneary's High Jump Kick missed Lucario, hitting the ground instead, and the ice around his impact point shattered with a crash.

Buneary shook himself, then Ash called for him to look out, and Buneary barely evaded before he would have been hit by a Metal Claw attack.

"I guess Buneary needs better steering in the air before trying that," Ash said, thinking, and glanced at Latias. "Flamethrower maybe? Or Water Pulse?"

"Can we try it now?" Buneary asked, evading a Bone Rush strike, then taking a hit from an Aura Sphere that sent him flipping halfway across the arena.

"Yeah!" Ash decided. "Okay, Ice Beam over there, then Bounce to it!"

"Break that ice, Lucario!" Maylene called.

Lucario reached the ice platform while Buneary was still in the air, and smashed it with a Force Palm.

"Kick off from Lucario, then!" Ash amended, and Buneary did just that. His kick wasn't quite as well centered as it would have been with the ice platform, but it was a lot, and the Bounce sent Buneary flying high into the air.

"Okay, NOW!" Ash added, and his ring lit up gold.

So did his amulet, before turning a reddish-purple colour.

Reggie, Maylene and Maylene's Lucario all stared in shock as Buneary suddenly exploded in size, going from a little rabbit about the same size as a Pikachu to an enormous rabbit about the same size as a Gigantamax Pikachu, then Lucario broke out of his shock first in favour of using Force Palm to block against the incoming Max Knuckle based off a High Jump Kick.

As it turned out, it was a lot easier for Buneary to aim when his foot was so much larger than his target.

He had to revert, then, to avoid tiring Ash out, but Lucario was a bit out of sorts after that and he wasn't quite as able to battle effectively.

It was probably something to do with how he'd just been driven into the marshy ground like a tent peg.

"That thing you did earlier," Reggie said, once Buneary had won the battle of attrition and Cynthia's Gastrodon was cheerfully washing down all four participants – along with anyone who'd been splashed by the Max Knuckle's mud splatter. "That was Dynamax, right?"

"Yeah," Ash replied, trying not to look too much like he wanted to fall over. "It's really tiring to force it like that, but it's a cool trick!"

"That explains why you wanted an outdoors battle," Maylene said. "And you've earned the Cobble Badge… Champion, how would you have dealt with a problem like that?"

Cynthia considered.

"It depends on the Pokémon, but with Max Moves you can do a lot by getting out of the way," she said. "Or by using Protect in the right way. A move like that can often break through a shield like Protect, but here the result would be to drive the Pokémon and their shield into the ground instead of breaking it – the ground was softer than the Protect shield would be."

She shrugged. "But it's easy to be wise after the fact. You did well – that was a tough challenge and you rose to it."

Then Paul came into the clearing.

"Oh," he said, noticing Ash. "I should have known you were involved with the giant Buneary."

"It's a pretty reasonable guess, you've got to admit," Latias said.

AN:

Max Moves can't miss in the games, but there's no such rule in the anime.