These are all my own opinions.
Characters in character
Try to keep the characters in character. If the point of the story is that the characters act differently, have some sort of reason for this, preferably. I mean, you don't have to, but it is my opinion that if a story is written about an existing character, one should be able to recognise that character in the story.
When writing stories from a character's point of view, this is the easiest sort to write if you have imagination; ie the ability to put yourself into somebody else's head.
This is where I, personally, have problems. Everyone must remain true to their writing style or the story will have no character (as in, quality, not person ^_^.). I have problems writing in the frank, sincere style a young person would probably think in (I have no memory of my thinking style before age 12 ^_^;). However, I try to include the sorts of feelings and thoughts that those characters might have, writing it in my own style, which is occasionally odd, language-wise.
But I could not write any other way, and I am not going to try.
I think fanfics are better when they are written in the author's true style. If you have a strong style you are not willing to compromise: good. Ignore most of this guide then. ^_^.
Don't be afraid to be serious and profound; true, it is Pokemon, a 'kiddie show', but we are here to explore new possibilities, why NOT make them more human, more real?
But who knows how those characters think? I think completely differently to the way I speak. This is how I am online; the way I type and write in stories is the way *I* think, whereas the way I speak is merely how I come across. It has little bearing on the real me. I have always wondered the style in which other people's thoughts come, but I cannot communicate my imaginings of such thoughts in written form - it's something I feel. If I become a better writer, perhaps I will gain that ability. That will be something worthwhile, to be able to adopt a full new way of thinking, as opposed to just another set of ideas. That is true imagination and true depth in writing.
New characters
More to the point, only new characters, or the fanfic focusing around them.
Be careful.
Make them believable. Give them a real personality; if they are mean and 'evil', give them motivation or some sort of twisted background. If they are seemingly perfect, show that they're not. People are human. Your characters should be too.
You may know bucketloads about Pokemon. That's good. Use knowledge to make things more believable and true. But, don't assume that your characters should have all that knowledge, particularly if they are beginners. In the Pokemon world, it seems there aren't extensive stat guides, locations of TMs, etc... having your main character be a Pokemon genius - unless that is their role, deliberately - is boring and unrealistic.
Also, give this new trainer - or whatever they are - a unique story. Unique background, unique motivations... who says they have to get their starter Pokemon from a professor, have a mean rival who starts around the same time as them, and strive to be a Pokemon Master? Why not have them aim to be a -insert Pokemon here- master, or a capturer of legendary Pokemon, or be training a bunch of Pokemon for a sports team, or be a Pokemon fashion stylist?
I dunno, possibilities are limitless, it seems Pokemon are a heavy part of potential careers in this (Pokemon) world. Like on the show, Misty wants to be a Pokemon doctor or water Pokemon master, Brock a breeder, Oak is a researcher, Ash and Gary are adventurers/aspiring Pokemon Masters, Snap is a Pokemon photographer, Tracey an artist...
The typical new trainer things are fine if you can work with them, but fanFICS - especially centering around fan made characters - ARE fiction, use your imagination and don't restrict yourself.
Remember one thing: ALL PEOPLE ARE HUMAN. This means, even bad guys shouldn't be totally evil and nasty. And, even good guys shouldn't be perfect. Pokemon does this well, by showing Team Rocket being nice to each other, having troubled pasts, etc, as well as giving Misty a hot temper and fear of bugs, Ash a tendency to brag or act rashly, etc...
Fanfics should, ideally, not be self serving - ie a thinly disguised attempt at writing a tale of you living out your fantasies - unless you've no intention of others reading it. I say this because such stories are rarely successful and can be boring, not because it is impossible to write a good fic on this. Putting yourself or your friends in a fanfic is a no-no unless it's a parody and you can pull it off.
There is a different between drawing from your knowledge of people, and using clones of those people.
Power in words
Use strong language.
Strong language doesn't necessarily mean using bucketloads of long words in each sentence. This, in fact, is a BIG mistake. Strong language is finding the exact right words to communicate what you want to say, and no more.
Detail can be a good tool. It is important to give a story some padding, also, so that the reader is not left unfulfilled.
However, it can also be boring. Use it carefully. If something significant happens, cut all excess words. For example, compare the following two passages...
"I stared in amazement, I couldn't believe what he did next. My eyes must have widened, I'm sure, blue rims outlined by white as I stared. What more could I do? He shocked me.
Instead of responding, instead of doing what I had predicted, instead of shouting or hitting me or pacing the room... he stepped out, left the room and closed the door behind him."
-or-
"Then he did the last thing I had expected. He left."
Do you disagree with me when I say the second 'passage' is a lot better? It is stronger.
Some may argue the first passage is better because it shows what she expected to happen, how it shocked her, how he left... However... can you see that the second paragraph portrays exactly the same thing? It just leaves a little more to the reader's perception and imagination. It's important not to give a reader EVERYTHING, or it gets boring.
If there was something significant about the way he left, something subtle (such as, I dunno, slamming the door, or looking at her before he shut it), that could be included.
But your own style may dictate a different means of strength in writing. Certainly a lot of people would disagree with what I just said. It depends... you might find it too bare for most of the story, but want to be sparing with your words at important parts.
Spacing
My computing teacher told me that white space is an important element in design and art. It is the same with stories. It gives the reader the opportunity to savour/take note of the words, as they stand out strongly.
It gives more impact. More meaning.
One finds it easier to read. That is important to understand.
See, I use white space even when writing non-fictitious prose. ^_^; Seriously, a common killer of good fanfics is when a person writes long, LONG paragraphs at a time, or even neglects to paragraph at all. I think in some stories, this has a place. In fanfics, it is USUALLY not necessary, and just discourages people from tackling it.
Inspiration
How does one come up with inspiration?
It differs from person to person. You know something, it is not even necessary to have an original idea for a fanfic. You could just take an episode and rewrite it - putting depth/character feeling into it, or parodying it... or take a particular character, and think from their point of view.
Personally (there's that word again) I don't get inspiration, I just realise I know what I want to write and write it. And then leave it in my outbox for about eight weeks before forgetting about it and not finishing it, hahah.
I can't tell you how to inspire yourself. If you need to force an idea for a fanfic, you could try just watching the show, or playing the game and picking up on some element in it. Or, read other fanfics and take an idea included and expand upon that (but take good care not to actually COPY the other fic and its originality).
Also, on this particular fanfic list, there are often 'challenges' issued. You can take up one if you are lacking inspiration but want to write. Just having a basic idea is an important step in forming a story.
Beginning or ending
The beginning of the story should show something of what type of story it is, to attract readers who like that type of story. That's about the only requirement. What I mean by this, is if it is a new trainer fic, it should be evident after reading the first few paragraphs. If it is a parody fic, it should be clearly different to a serious one.
The only reason I'm saying this is because I depend upon both the title of a fanfic and the first couple of paragraphs. I can't afford to spend time reading every single fanfic, so I skim through my mailbox, and ignore all the ones that look like new trainer fics, or which are continuations of fanfics for which I have not read the first few chapters. ^_^;
So, the beginning of the fic is what you use to attract people to your fic, to convince them to read more. This is important. However, it cannot compare to the significance of a strong ending.
The last sentence of a fanfic is the most vital one.
A story could be not-very-good, but end strongly, and then people would remember it as a quality fic.
Not all stories depend on their endings; some have their strength lie within the story, and the ending is just a necessary part of that. But the majority of fics should have a strong ending. Meaning, one that either lets us know the meaning behind the fic, what it was all for. Or, one that shocks the reader, especially after they had almost relaxed into the fic.
Open endings are an interesting tool also. They leave the reader with something to think about. And also demanding a sequel. -_-; Whether or not this is your cup of tea is another matter.
I often write my endings first, they're what make me write the fic in the first place. It's pretty obvious which of my stories do this, they're the ones with no interesting plot (or no plot full stop) which do nothing but end. Don't be like me. An ending is vital, but it's, like, kinda nice for your fic to be decent too? ^_^.
Parodies
So, I've been assuming you are writing a serious story. As far as parodies go... anything goes. Different people find different things amusing, so go with what you find easiest and most effective. I guess it might be more difficult depending on the level of your own sense of humour, but a tip - if you can read through your OWN humourous fic, and smile or laugh at any parts - you're pretty much there.
Now for some bad (^_^.) advice. In parodies, be a smartass. Have your characters have little snide/sarcastic responses to other characters. Simple elements like that are very good in making a fic humourous.
Title
I read once that a title has very little reflection on the quality of the story. This is a statement I strongly disagree with.
You can go two ways:
1. Tell people pretty well what to expect in the story. This includes things like "Brock gets lucky", "Anon's Journey", "Pokecenter Panic" and "Revenge of the Magikarp". This sort of title can be boring, but it can work in giving people a hint as to whether they'd like to read it or not.
2. Be obscure. Use words you like that fit the style of the story. Choose whichever word you think truly sums up what your story is; it does not have to be obvious. If you wanted to put real meaning in your story, sum up that meaning in a word or two, and give that as the title of your fic. Or, the title could even show a hidden meaning, the gravity of which will only be understood after having read the story.
The last of those is difficult to use, but powerful.
My own technique for titling stories...
After I come up with the idea and start writing, I'll go through maybe half, three quarters of the fic before I start thinking about titles. I look through the story to see if there are any recurring themes, or to see what I was trying to say. (Sometimes I don't know what I meant until I've written it. ^_^;) Then I'll find a word or two that sums that up very nicely.
Or, if I find traces of a theme that could be emphasised more strongly, I'll give the fanfic that title, and for the remainder of the story, keep that title in mind - so that my ending can correspond with the title.
Some mightn't be understood by every reader. I have a fanfic series (which SO needs updating) called 'Sincerity', which may seem like an obscure title if you've read it. But, I knew what it meant... I was trying to write about the characters as real people rather than 2D, mundane cartoon character. When they would act the way that a real person might - cutting away cliches and stuff, that's sincerity. My ending for Sincerity (yes, I have written it... I just kinda haven't written everything in between ^_^;) emphasises the title.
References
Feel free to throw in mentions of other TV shows, music, anime, sports, etc etc. Although do bear in mind that when you do that, a LOT of people won't know what you're talking about. Also, and this is just my opinion, I think that the Pokemon world is quite different from ours - like, they wouldn't have the same stars and same culture as us.
This goes double for crossovers; crossovers are fine, and great for the reader who has knowledge of both shows, but just bear in mind that you will exclude a lot of your potential fanfic reading audience. People reading Pokemon fanfics have one thing in common - they know something of Pokemon.
Additionally - if the story you are writing is in English, try to KEEP it in English. If you have a character who is deliberately of another nationality, sure, have them slip up on a few phrases, but... I guess what I'm trying to say is, believe it or not (gasp, gasp), not everyone knows the meaning of words like 'kawaii' and 'baka'...
This goes DOUBLE for fanfics based on Ash and his friends - they do not speak Japanese on the show, so why should they in stories?
General
Be careful with spelling and grammar.
Don't force yourself. Unless you feel you can't bear to leave your story unfinished for another day. ^_^.
Check your facts. If you are deliberately going against the grain (for example, I dunno, having a Caterpie defeat a Moltres), fine - try to make it believable - but don't fumble on everything. If you think you don't understand something, ask someone, or leave it out.
In longer stories, serious scenes can work well if offset by humourous or casual ones. A bit of lightheartedness doesn't hurt. This does NOT mean something like:
"Everyone stood there, just looking, saying nothing. It was a small but powerful sight; Pikachu, their friend, Ash's friend, of so many years, lay dead...
Brock grinned. "That was pretty... shocking!"
Misty nodded. "You could say all the spark's gone out of him!""
Okay, stupid example. I don't know why I said that. Maybe I just wanted to make bad puns. Don't we all? ^_^.
Character emotions are powerful. Use them at your discretion. Remember that although the characters are only human, they are still quite strong. I'm not really fond of fanfics that spend the whole time with one of the characters crying hysterically or something.
Serious scenes shouldn't come out of nowhere or they won't be taken seriously. Try building up to key moments. If Misty suddenly out of nowhere says "Ash, I love you", people will think 'hmm, this seems very tacked-on to the plot'.
If you're writing a saga, ending each chapter with some sort of interesting cliff-hanger is the way to go, because people will want to read the next part. But don't go overboard. ^_^;
