Hm, sorry you had to wait so long to get a grade for this. ^^;
: It was a cute and traditional tale of a trainer going on an adventure into the forest to catch a Pokemon. You told it nicely, and the Ghosts hypnotizing the Wurmple to be their sort of minion was unique. However, while fine for the Easiest rank, these concepts tend to be graded harshly in higher levels.
You can write about anything you'd like. Whether you want to take your main protagonist on adventure across the ocean or into outer space, coming up with something the Graders haven't seen or read before is a great way to improve your odds of capture. :P Try brainstorming some original ideas so that your story is both creative and one of a kind. :3 Let your imagination run wild; there are few limits in the Story section.
: Your spelling and sentence structure was very nice. But the lack of paragraphing was a bit of a stump here. Sentences that tell of a single topic or idea belong conjoined into a single paragraph. A new paragraph begins when a new idea or situation begins.
"WUR! Wurple wur...wur..." Said the Wurmple.
Something else to keep in mind, is that when using dialogue, the phrase referring to the quote is considered part of the same sentence. "Said the Wurmple." is a dependent clause; it requires the quote to be a complete sentence. The dialogue tag should be lower-cased unless it begins with a proper noun and requires capitalization.
"WUR! Wurple wur...wur..." said the Wurmple.
There was some good stuff here, especially when you described feelings such as fear and excitement. The visual descriptions were quite scarce though. I don't know what your character looks like, nor can I see the scene around them. Use adjectives to paint a picture for your reader. Colors, sounds, smells... Translate what your mind sees into your text, and we will be able to see it as well.
Was the grass, damp? Dry? Sharp? Soft? Was it green and wick or dull and dying? Were the trees tall and broad? Was it sunny or raining? Hot or cold? These details create an atmosphere. Half the joy of reading is feeling like the reader themselves are in the story as well.
: Being your first story, I think this is just fine for the little worm. It was a little shorter than preferred, but it was a fine piece. I think you are capable of coming up with some really good stuff if you put the time and effort in. Keep in mind that stories will get graded more harshly the higher up in rank you go. Writing takes practice and there is always room for improvement.
Enjoy your Pokemon.