I wrote one once, called Why Fire Red Stinks. I never finished it, you're right. I didn't do it in script format, though. It was more . . . the internal thoughts of my character.
EG:I meet Professor Oak. I get a lecture about stuff I already know.
I am a boy.
My name is Grey. Yes.
This is Oak’s grandson. He’s been my rival since we both were babies.
His name is Brown. Yes. This old man has Alzheimer’s.
My very own Pokémon legend is about to unfold! Whuppee.
A world of dreams and adventures with Pokémon awaits. I’m so excited. Not.
I played with the NES. Okay! It’s time to go!
I booted up the PC. I withdrew a Potion. What’s this? I’m not Harry Potter...
I talked to my mom. Apparently all boys leave home someday.
How did you know that?
It said so on TV.
Oh well, that explains it. TV is always right.
And Professor Oak from next door is looking for me. Creepy.
That’s it? I just get kicked out? I’m ten, for crying out loud!
...Fine. See ya!
I went next door, but the only one there is a girl with a map.
It’s Daisy. She reckons her brother, Brown, is out at her Grandpa’s lab.
Your grandpa? Remember, I’m a noob Trainer. I don’t know your Grandpa! Sheesh...
Fine. Just ignore me.
Hang on...the letterbox outside says “Brown’s house.”
But I thought that Mom said the Professor lived here!
I enter the lab and talk to some guys in white coats.
They both study Pokémon as Professor Oak’s aide. I never would have guessed.
The woman in green just gushes about how wonderful Professor Oak is. Blech.
There’s a guy with brown hair. Let’s chat to him.
What, it’s only Grey? ONLY Grey? Who does this guy think he is!
And Gramps isn’t around. Everybody but me has a grandfather in this town!!
Hold on... Maybe this is Brown! That would make sense.
Then he’d be Daisy’s brother, and Oak would be their grandfather. Dilemma solved.
...and so on, up till about Pewter City, I think.