TheRandom500 request.

A battle of wits, that's what this was now. A battle whose outcome was determined by who could give the most effective commands the quickest. One mistake could spell a loss. This was no time for reckless...
"Emboar, use Head Smash!" Diantha blinked in surprise at her opponents choice of move.
"Mega Gardevoir, Psychic" That one command was enough for the white humanoid Pokémon to stop the incoming assault of the large flaming boar and send it flying across the room and into the wall.
"Emboar!" Her challenger, a rather confident and spunky girl from Unova by the name of Hilda, called out to her tusked partner. A quick glance at the screen at the side of the room told her all she needed to know, however. The bar that signified her Pokémon's health was empty. The girl ran over to the slumped form of her partner and took out a red and white ball with a button on it whilst she petted him.
"You did great Emboar, take a rest." She told muscular bipedal hog, a red beam shot out of the ball, covering the Pokémon in its light before retreating back to the ball, the beast now safely inside.

Diantha watched the whole exchange and smiled. The girl really loved her Pokémon, but she wasn't the best with tactics. She was very rough and tumble as well, if her tank top, sleeveless jacket, very short shorts and slang heavy dialect were anything to go by. However she was still very pretty, probably would be quite beautiful if she cleaned up a bit. Diantha blinked and smiled. She'd just formed an idea that could benefit both of them. She looked to her partner who had a look of recognition in its calm red eyes. Smiling Diantha calmly walked over to Hilda.

Hilda just stared at her Emboar's Pokéball running the battle through her head again and again to figure out where she went wrong, but consistently she came up with nothing. She was broken from her musings by a shadow looming over her. She turned and looked up to see Diantha's calm smiling face.
"That was a very good battle, well done." The champion paused before continuing. "Not many people have lasted so long against my Mega Guardevoir." Hilda looked to the Pokémon in question, now standing next to it's trainer. Both were elegant and gave off an air of calm authority. Curiously, although the battle was over, the green headed Pokémon hadn't reverted to its normal form.
"Thanks." Hilda replied, standing up and returning the Pokéball to her bag. "Still don't know where I went wrong though." She sighed.
"Well, you were quite reckless with that last attack, in fact, you were quite reckless throughout the battle." Diantha mused. Hilda didn't respond but did look like she considered the possibility, so the brown haired woman continued. "How about I help train you." She offered.
Hilda jumped slightly out of shock. "You'd do that!?" she asked, failing to hide her excitement. When The woman opposite her nodded, smiling, the ponytailed girl jumped for joy. "Sweet!" She cheered. "When do we start?"
"Well, I'll need something from you first." Diantha's smile shifted from calm to nervous quite quickly. "I'm very busy with both my acting job and being the champion, so I'll need you to be my P.A. whilst I train you." Hilda's expression also turned nervous.
"Oh, umm, yeah. I think I'd be kinda out of place at all the places you're expected to go." She mumbled, rather downcast.
"Oh don't worry, there's a way around that." And before Hilda could ask another question, Mega Gardevoir glowed and released a thick, pink mist.

The mist swept over Hilda quickly and started a change. Her jacket and shorts turned the same colour as her top and melded; the clothing combining together and lengthening to her knees and becoming a silk dress, the hem of which turned a light purple. Excess material from her jacket separated and combined with her cap, the pink on which having bleached to white and the whole thing changed material. The hair tie she used for her ponytail undid itself, letting her hair fall down to the small of her back. The tie lengthened and turned to a pink ribbon, tying itself around the new sun hat into a bow. Her trainers shrank into white pumps and lastly, her pink shoulder bag became white and morphed into a handbag, her Emboar's Pokéball hanging off the strap. Hilda looked down at herself in both shock and awe.

"What the... how?" Hilda spluttered, utterly confused.
Diantha giggled. "Mega evolution brings out new powers in a Pokémon, many of which can't be entirely explained." She told the discombobulated girl. "here, come, take a look." She added, taking the stunned girl to one of the reflective windows in the champions room to see herself.
"Eh, but... wow, is that.. me?" Upon seeing her reflection. Hilda was left speechless.
"you wouldn't be out of place around me now, would you?" Diantha asked.
"No." Hilda sighed, before she started worrying again. "Oh, but, I'm not sure how to act proper or anything." She told the older woman.
"Hmm, well, We could always hypnotise you to act the part until you think you've got the hang of it." She mused.
"Hmm, that might work, let's try." Diantha blinked, she wasn't expecting that suggestion to be taken seriously.
"W-well, ok, if you're sure." She sighed, nodding to Gardevoir, who had returned to normal. The Green headed Pokémon nodded and unleashed a hypnosis on the spunky trainer her partner had decided to take on. Hilda was willingly absorbed by the attack and was soon under the spell, and with a quick command from Diantha, was soon snapped out of it.
"Oh my." Hilda spoke, her posture being less of a tomboy and more of an elegant lady. "That felt most unusual. Oh." she giggled softly at her new speech and mannerisms. "This will take some getting used to.". Diantha joined in giggling.
"Wow. A bit more extreme that I expected, but I guess it will do." The woman sighed.
"Yes, it should be most adequate." Hilda replied. The two white wearing women laughed a bit more before Diantha began telling The new Lady what she'll need to do as her apprentice.