Mauville Racing Grounds' facility was enormous indeed; while the office space had little signage due to its size being on the smaller side, the property where the action took place, just outside the city proper, was enormous. Luckily, Josh had experienced staff who knew the facility well, and signage that could guide challengers to the correct location. They would not immediately find the Leader; instead, at the front desk was his secretary. The young man with well-cut hair would get Gwyar Wledig checked in.

The wait wouldn't be too long; Though his volume was picking up, he was still quite organized and punchtual. Once it was time for their appointment, the voice of ANDREW WEISS, Josh's scheduler, echoed over the Gym's loudspeakers:

"Challenger Gwyar Wledig , please report to the Main Sector. Challenger Wledig, to the Main Sector. Thank you!"

Provided Gwyar followed the ample signage to get to the Main Sector, where the facility's battle courts were located, they would find Josh removing the saddle from Toralf, a giant Raichu that looked ready to run. Next to the electric rodent was a bare-backed Rapidash whose blue mane blazed bright as a distant star. "Gwyar! Great to see you!" he greeted his fellow Gym Leader. "How's business been in Mossdeep?" While most Gyms' battle courts had some variance to how large they were, Mauville's was notable for being extremely large; it was triple regulation size, and it was wide open, with plenty of channels for aquatic Pokémon to swim. Pokémon had plenty of room to run and nowhere to hide, playing into the ultrafast Pokémon on Josh's Gym squad and giving them quite the home field advantage.

The Gym Leader and Champion directed the challenger toward the west side of the triple-sized court, toward the Trainer's Box on the challenger's side. "According to your application, this will be a two-Pokémon Doubles match. The first side to incapacitate their opponent's entire Pokémon team will be the winner. This match will have a seven-minute time limit, and ties will be broken by sudden death. Good luck to you; you'll need it."

Once the two trainers were positioned, the small gallery cheered, primarily for Josh, as the platforms rose to a height of roughly ten feet. The Gym Leader pointed toward the circular pool surrounding the inner ring of the battle court, the Rapidash and Raichu ready to do battle. "Now, bring forth your Pokémon and ponder your opening move. I can assure you it will be the only decision you will have time to think on," Josh taunted.

Vs Mauville Gym

ft. Josh Devlin

"It goes well. Thank you." He replied from his end of the arena, polite as ever. "I hear the same can be said of Mauville."

As the Mauville gym leader explained the rules, Gwyar's pokemon performed little rituals. His Archaludon did old woman stretches, her body lengthening into a vaguely bridge-like shape, whilst his Runerigus assembled and disassembled herself repeatedly.

As the explanation drew to a close, the both pokemon snapped to attention.

As Josh finished with a little taunt, Gwyar simply and promptly said:

"Begin."

Still in her fully lengthened state, the archaludon did not bother to change as her many arches compressed together sharply, before popping apart with a booming crack akin to a shotgun blast.

The Metallic Sound cut through the large arena at, naturally, the speed of sound, painful like nails on a chalkboard as the Runerigus leapt over the steel dragon, hovering above her, and spread out its many dark limbs apart, the markings etched unto the stone glowing a dark violet as a large Shadow Ball blasted towards the Rapidash.

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TL;DR:
-Archaludon used Metal Sound.
-Runerigus used Shadow Ball on Rapidash.