There's nothing wrong with your grammar, really. Spelling's great, so's grammar. But from what I can tell here, you're going too fast. I had that problem too when I first started writing. In my head, things were already played out, and I could see it all like a movie and such. (idk 'bout you, that's probably just me ranting buuuut yeah :P)
So anyhoo, you have to remember that your reader has no clue what's going on in the story! They can't see into your head. It's all up to YOU to show them that little movie playing in the back of your mind. When you drop them in they want just enough detail for them to understand what's going on. Slow down -- it's fine. Nobody's going to hate you for it. Give us time to understand the characters. For example:
I stood in the deathly silence of what they called the Acuity Lakefront. The snow was falling lightly, covering everything with a layer of white, like the powdered sugar on a human's treat. I don't think anyone has ever actually seen the grass surrounding Snowpoint City, even in the summertime it remained as frosty and cold as ever. I opened my eyes and looked around. The sky was gray-white and depressingly bleak. The pine trees surrounding the area were covered in snow and strung with multicolored lights and stringy garland, along with ornament bulbs. Christmas. Another pointless human celebration. In the distance, I could see two shapes vaguely, moving in circles around each other. No doubt another Pokemon battle. Something I had hated since.... no. I'm not even going to go there yet. I shook myself off, turning my mind back to what I needed to do. Jazz was coming, and I needed to check on something.
This was a nice peek into Spazz's head, nice way of setting the, well, setting, and I thought it was pretty interesting to get to know his personality better, though it might've been better to split that up into smaller paragraphs. Don't be afraid to use that enter key of yours! That blank spacing is actually quite appealing to the eye!
For example, you could have made it into:
I stood in the deathly silence of what they called the Acuity Lakefront. The snow was falling lightly, covering everything with a layer of white, like the powdered sugar on a human's treat. I don't think anyone has ever actually seen the grass surrounding Snowpoint City, even in the summertime it remained as frosty and cold as ever.
I opened my eyes and looked around. The sky was gray-white and depressingly bleak. The pine trees surrounding the area were covered in snow and strung with multicolored lights and stringy garland, along with ornament bulbs.
Christmas. Another pointless human celebration. In the distance, I could see two shapes vaguely, moving in circles around each other. No doubt another Pokemon battle. Something I had hated since...
No. I'm not even going to go there yet.
I shook myself off, turning my mind back to what I needed to do. Jazz was coming, and I needed to check on something.
So you see, the spacing of that paragraph gives it more, how do you say, emotion to it in a way. Do you see how it gives more impact to that
no, rather than if you clumped it together into one paragraph? Plus it's easier on the eyes! 8Db
Spacing is not just a courtesy. It's your tool, Oh Mighty Writer, a weapon in your Awesome Author Armory for you to use! Read your sentences out loud, and you should be able to naturally feel out where to space.
Moving on now, brave soldiers~!
Like I mentioned before, that little quip was a nice peek into Spazz's character. But shortly after that crisp intro is a sudden betrayal by the narrator's brother. Here, I'm afraid, is where you're most likely to have your audience go, '
Wha?'
The main problem with your story is that you're just moving way too fast, leaving us with too may questions.
Why does Spazz's brother suddenly betray him? Where did he get this sudden whim, that Eevees are more awesome than any other Pokemanz? Is he Hitler!Eevee in disguise?
Of course, I kid about that last question, but those are the questions you leave your reader with. In one chapter you have Spazz betrayed, meet a brand-new random Pokemon pardner, and then head straight off to Mt. Coronet! And there's still the question of how exactly these Eevees can harness the energy of the evolutionary stones and such.
Chapters were never meant to cram in some much action. Not every chapter
has to be so chock full of plot devices that it falls on its own weight. For example, you could have designated chapter one to introduce Spazz and Jazz, then chaper two to foreshadow Jazz's BWAHAHAHAHA EEVEE TAKEOVER TIMEZ.
Sometimes I fnd it helpful to write out the plot in one sentence. For example, something like 'Nazi!Eevee wants to take over the world with evolution energy, and his brother must stop him with the help of his friends.' That way, I have a general idea of what's going on. After that, I'd list out a few events that'd happen in the beginning, and maybe a few in the middle and the end.
Sometimes, to help myself out when I'm writing the stuff in the middle, I find helpful to write out the ending in a sentence, so I have a sort of idea of where to steer things. Even somethng as simple 'main character dies' can shape a lot in your story and how you write it as you go along.
Um, long rant wrap-up? Winging it is great! Planning is great! Combine both of them, and it will be Supergreat, like Superman! (Okay, bad pun.)