Well, I'm not going to write a whole one-shot, but this is what I've got:
The hyper beam hissed through the grass, slender blades puffing to ash as the column of white energy ripped through them. Ninetales was ready, crouched and alert, and a kick of his hind legs had him bounding out of the way of the attack, fire welling from his jaws and billowing through the air towards the dragonite that had fired the attack. Jane squinted and shielded her face with an arm as the energy attack whined past to her left, striking a tree trunk with a vicious crunch and eliciting a rain of leaves and twigs as the huge oak shuddered with the impact. The beam vanished as Dragonite took the flamethrower full in the chest, though the hulking orange dragon seemed more annoyed than actually hurt by the attack. The fire splashed off the tough scales on his stomach as easily as water.
"Come on, Jane, even you know that fire's not going to work in this fight," Bobby called across the field. "Let's have a water pulse, Dragonite."
The dragon snorted, spitting a ball of water at her opponent. Ninetales had already faded back into the grass, though, using his smaller stature to his advantage. The water pulse burst harmlessly, flattening a small area of grass but doing nothing to harm its intended target. Ninetales was on the move, nothing but the shushing of the grass marking his position as he slunk through it, low to the ground. Dragonite spat another water pulse into the grass, but once again, Ninetales was gone when the attack struck.
"Get in close and use iron tail," Jane said, then shuddered, glaring down into the grass in front of her. The unusually thick growth, up to her waist, was perfect for concealing Ninetales as he circled his chubby foe, but it certainly did have its disadvantages. The long blades tickled her legs and her bare stomach--yes, maybe her mother had been right about short shorts and a midriff-bearing top not being the best adventuring gear ever designed, but Jane wore what she wanted. Every time she moved, it felt like little creatures were crawling all over her skin. Of course, Bobby wasn't similarly bothered, being the poster child of unreasonably baggy clothing as he was. His shirt probably stopped somewhere around his knees, though of course Jane couldn't see thanks to the grass.
Jane blinked, a choking noise catching her attention. To her horror, she found Ninetales hanging by her neck from Dragonite's paw, the dragon's stubby claws buried deep in the fire type's luxuriant ruff. The scales down Dragonite's side were smashed and partially torn away, indicating that the iron tail had been a success, but the attack had also given Dragonite the perfect chance to strike. Ninetales scrabbled at Dragonite's beefy arm with his forepaws, but his claws only rasped off the dragon's tough scales, and the frantic kicks of his hind legs had about as much effect. Jane was forced to scurry out of the way as Dragonite hurled her partner right at her, Ninetales crashing back to earth in an undignified heap.
"Daydreaming, Jane?" Bobby said. "I expected better. You really are worthless, aren't you?"
"Says the boy who bought a magikarp off a traveling salesman because he thought it was a rare and mystical pokémon," Jane drawled, playing for time while Ninetales pulled himself together, shaking dirt from his creamy fur as he got back to his feet. Much though she hated to admit it, Bobby's dragonite was too strong to take head-on. Time for a little deception, then. "Confuse ray, ninetales."
"Safeguard!" was the hurried countercommand, but Ninetales had already flared his flowing tails, their tips glowing with golden light. Dragonite raised her paws, green energy bubbling out from her palms and forming a film in the air before her face. Her eyes were on her opponent, though, and on the gleaming lights swaying through the air as Ninetales waved his tails back and forth. In a trance, she lowered her paws again, the green light fizzling out as she watched the hypnotic dance of Ninetales' tales. Oblivious to her trainer's angry howls, she gave in to Ninetales' spell and suddenly found her vision clouded by thousands of tiny stars, winking and dancing as they flitted in and out of view.
Dragonite growled, waving a paw in front of her face. The glimmers still eddied around her vision, though, swirling more frantically than ever. "Now, confuse her with faint attack!" Jane said, and Ninetales took off, shooting through the grass with unnatural speed. A shadowy blur, he leapt from the grass and slammed into Dragonite's side, then bounded away and began circling again as Dragonite staggered and let out an angry roar. Her movements were sluggish and uncoordinated, her antennae twitching as though she hoped to pick up some sign of her opponent even as her vision was clouded by the confuse ray.
"Keep it up, Ninetales," Jane said, her voice as calm as ever.
"You think you've got the upper hand, huh?" Bobby asked, even as Ninetales slammed into Dragonite's back and darted away before the confused dragon could retaliate. "Try this on for size. Dragonite, outrage!"
"Get out of there!" Jane yelled, but her voice was drowned out by Dragonite's wild howl. Blue and green flames exploded off the dragon's scales, cloaking her in a veil of dragonfire even as she began to thrash and strike wildly at the air. Ninetales, coming in close for another faint attack, took a tail to the side and was hurled across the arena and into a tree. Dragonite stormed around the arena in a blind rage as Ninetales slid to the ground, his dark aura gone and his breathing harsh. "Move, move!" Jane yelled as Dragonite blundered closer to him, throwing sheets of unnatural fire in all directions. The dragon flames didn't ignite the grass that covered the arena, but neither was Ninetales protected against them as he was against ordinary fire. He raised his head as the burning dragon raged nearer and got shakily to his feet, limping away from the tree.
He couldn't take another hit from outrage, Jane thought grimly, and he was in no condition to dodge now. Dragonite bore down on him in senseless rage, flailing claws cutting a deep gash in the bark of the tree Ninetales had just left. She had to stop Dragonite from getting in another direct hit. "Ninetales, stand your ground and roar."
There was a moment of hesitation--Dragonite had turned and started floundering in Ninetales' direction again. Come on, come on... Jane thought, fists clenched. You can do it...
Ninetales raised his head, flaring his tails to their fullest, most impressive height. Dragonite couldn't see, blinded by raging dragon energy, but she could certainly hear. A huge roar escaped the fox's throat, cutting through even Dragonite's fevered howling. A moment of dead silence followed the noise, Dragonite stumbling to a halt, her fiery aura flickering and starting to falter. The confused pokémon swayed, head turning to and fro as she tried to locate the source of the noise through power-clouded eyes.
"Just keep roaring," Jane commanded, pressing her hands over her ears.
Another shattering roar split the air, and now Dragonite actually staggered back. Bobby, who had gotten a lot more of the noise than Jane, was bent down, eyes closed to slits and palms ground into his ears. Dragonite raised her paws, too, but they didn't do much to block out another roar. The big dragon's eyes were wide and rolling back and forth around the arena, still clouded by the confuse ray, and her breathing came in whuffing gasps of distress.
"Dragonite! Dragonite, listen to me!" Bobby yelled, but more roaring blocked out his words and drove Dragonite deeper into panic.
"Now run at her and roar one more time!" Jane yelled, unable to contain her excitement. Oh, how the tables had turned.
Dragonite had had enough. The sight of an indistinct cream-colored blur rushing straight at her, emitting an incredible blast of noise as it came, was enough to set her to flight. Spreading her dainty wings, the dragon kicked off in a surprisingly graceful motion, soaring up and out of Ninetales' reach.
She easily smashed through the lower branches in her way, but as she continued up into the dense canopy none too far overhead, limbs reached out from all sides to ensnare her, cutting thin lines of pain down her orange body and tugging at her limbs. Clawing branches tore into the membranes of her small, delicate wings and she screamed, twisting and thrashing in blind desperation, tearing limbs off of trees but only entangling herself more hopelessly.
"Now, Ninetales! Finish her off with heat wave!"
"Stop, Dragonite! Just calm down and get yourself out of there!"
Ninetales tipped back his head, exhaling a searing wave of breath. Superheated air rushed up to surround dragonite, the leaves around her flashing into ash almost instantly. The dragon was caught in a curtain of flames as Ninetales poured on more and more heat, branches above Dragonite catching fire and showering her with flaming twigs. The dragon wailed and struggled; everything was burning, burning, even the air she gasped into her tired lungs. She choked and flailed, tears flashing to steam as they leaked from beneath her closed eyelids--and then it was all gone, vanishing in a flare of cold red light.
Bobby clipped the pokéball back onto the belt at his waist, grimacing as he ran his fingers along its companions. "How do you like that, Mr. Dratini Starter?" Jane asked, not bothering to contain the broad grin stretching across her face. Ninetales broke off his attack and turned cool eyes on Bobby, flaming leaves raining down around him and starting small fires in the tall grass.
The potential for catastrophic forest fire didn't appear to bother Bobby; he pulled another pokéball off his belt and smirked. "Not bad, Jane, not bad. It's going to take more than cheap tricks to get past this guy, though. Let's go, Gyarados!"
Hardly a masterpiece or a particularly high-octane battle, but I hope it helps.