Variation 1 by ImoutoCommissions

   The first thing that strikes Ash about his newly-human Pikachu is 
that she's a girl. His best friend
   and closest companion has been a lot of things to him, but he's never 
once thought of her as a girl.
   But considering the fact that she has no clothes on, there's little 
room for debate on her anatomy.
   Other than the obvious, she has tanned skin and blonde hair that is 
almost yellow, and she's small,
   reaching only his chest at full height. She still has her ears and 
tail, and her bright red cheeks,
   however.

   She's so immediately excited to see him that she tackles him to the 
ground, hugging him close and
   ignoring his cry of surprise. Having a body like that so close to him 
is odd, but he tries to treat this
   as any normal time with his beloved friend. Little does he know, 
she's trying to take advantage of
   her more human form to gain his interest, and when the group resumes 
their journey, she frolics
   about with no concern for her lack of clothing.

   From time to time, she likes to bend over to try to give Ash a nice 
look at her girlhood, hoping that
   this will entice him a little more. When night rolls around and he 
allows her to sleep in his tent
   with him even in this form, she's certain that her efforts must have 
paid off.

   But then he gives her a pat on the head and tells her goodnight, 
rolling over in his sleeping bag
   and falling asleep quickly, just like he always does. She's so 
disappointed that she can hardly
   stand it, and, even though she tries to go to sleep on her own, she 
can't get over her disappointment and is soon reduced to tears.

It isn't long before the sound of her sobbing wakes Ash back up. "What's 
wrong?" he asks, immediately noticing her puffy eyes.

She sniffles hard and looks up at him, muttering, "I've always had 
feelings for you, as more than a Pokemon and a trainer. And even though 
I was happy just being by your side as a Pikachu, now that I'm...I'm 
not, I don't want to waste the opportunity! But you really didn't even 
notice me..."

"I noticed you," he replies, pulling her into a tight hug. "What do you 
want?"

"Can I have a kiss first?" she asks tentatively. "On the lips?"

Ash nods softly, pulling back so that he can press his lips to hers. At 
first, she's just content like this, but before he has the chance to 
pull back, she decides to do something to prolong the kiss. She deepens 
the kiss by pressing her tongue between his lips, working it into his 
mouth. Ash, while stunned at first, eventually catches on after enough 
coaxing, and returns the depth of her kiss, working his tongue into her 
mouth as well. Soon enough, the two of them have relaxed completely, and 
Pikachu feels her arousal overtaking her.

When the kiss finally breaks, she's able to see the tent in Ash's shorts 
and knows that he's feeling the exact same way. Pleased, she says, 
"Now...I want you inside of me," she says as she pulls his cock free and 
begins stroking him to a full erection.

"Huh? Inside?" he asks, visibly confused, and she spreads her legs, 
pointing between them. "Don't you see the hole here?"

"Uh...right, right!" he says, and he climbs so that he's on top of her, 
trying to figure out how to fit inside of her. However, he's so thick 
and she's so tight that they aren't able to get very far.

"I have an idea!" she says quickly, not wanting to give up. "You should 
use your fingers to stretch me and your tongue to make me slippery!" 
Even as she speaks, her face goes so red that it matches her cheeks.

Ash does as she says, fingering her while he leans down to lick at her, 
clumsy due to his lack of experience. Still, she has just as little 
experience, and every bit of it leaves her more pleasured than she's 
ever been before. She wraps her legs around his neck and tangles her 
fingers in his hair, her cheeks sparking as her pleasure mounts.

Her moans grow more and more incoherent until she's reduced to, 
"Pi...pikapi!" and the like. Ash does what he can to keep up the things 
that he knows increase her pleasure, and it isn't long before he brings 
her to orgasm, causing her to send out an electric shock that leaves him 
tingling all over.

This time, when he tries again, he is just barely able to fit inside of 
her, and she grits her teeth as he tears her hymen, pushing into her. 
He's only able to fit half of his length inside of her, and though he's 
overcome with pleasure, he notices fresh tears in her eyes and makes to 
pull out, not wanting to hurt her. Pikachu, however, says, "I'll send 
you blasting off like Team Rocket if you even think about it."

So he doesn't pull out, and she recovers from the pain, before 
explaining to him how to push in and out, and he begins thrusting just 
as she instructs. It isn't long before she's reduced to a panting mess, 
writhing beneath him with her cheeks sparking once again.

"Harder," she begs him again and again, "faster!" And Ash does as she 
asks until he's battering against her cervix, harder and harder until he 
finally breaks through, pressing into her womb with such sudden force 
that they're both sent into orgasm, with Ash spilling his seed deep 
inside of her and Pikachu letting loose her electricity in a Thunder 
Wave.

After she catches her breath, Pikachu rolls so that she's on top of Ash, 
who is paralyzed from the sudden attack. "I'm sorry for shocking you," 
she says, nuzzling against his chest, and it isn't long before the two 
of them fall asleep together.

~X~

When he wakes up in the morning, the paralysis having worn off in the 
night, the first thing he notices is that the spell has worn off and 
Pikachu has returned to normal again. The second thing he notices is a 
yellow egg with black markings.

"Huh? Where did this come from?" he asks in confusion, but Pikachu knows 
that it's her egg, and that he's the father.

She does her best to kiss him as she nuzzles him, wanting to express her 
gratitude for the night before.