Help With Oneshot's

I have an idea for a Oneshot, but I've never written one before and I don't know how to go about doing so.
Let me just jump right in with what I need help with...

1. What is the average length of a Oneshot?
2. What must a Onceshot include? (introduction, conflict, conclusion, etc)
3. If the Oneshot is about characters from the franchise and yet the idea isn't canon, does it matter how you go about portraying it?

Thanks to anyone who bothers to help.

1. A one-shot must be as long as it needs to be. Don't think about how long other people's are, just think about your story and what length suits it best.

2. A one-shot is generally a self-contained story, so it should contain everything you listed. The idea behind a one-shot is that it isn't a fragment of a story, but an entire story that isn't divided into chapters.

3. If you're using characters from one of the Pokemon canons, it's important to be consistent with characterization. The characters should act like they would if it were a canonical story. As for any events you make up, just be sure that they don't contradict any canonical events, and it should be fine.

To add to what icomeanon's already said, let me just define what a one-shot is.

A one-shot is simply a fanfiction that has only one chapter, one installment, one whatever-you-call-it. It's a story, but it's done in one shot (hence the name). In a sense, you could call it the equivalent of a short story, as it's meant to be written completely without breaking chapters and for the purpose that a person can simply sit down and read it in one sitting. (Chapters imply that the reader gets to take breaks between them, so we're assuming that you're not the kind of person who reads an entire epic in one go here.) So, for the first two questions, the answer here should be what icomeanon said because a one-shot is a complete story in one chapter. Period.

In other words, imagine everything you do for a longer work and cram it into one place. You don't limit yourself with a chaptered work or serial (or you usually don't). You don't limit certain plot elements. It's no different in terms of storytelling compared to writing a serial.

As for your third question, to add more detail to what icome said, I give you my rant on keeping it canon and why canon doesn't like to be raped. I could simply just answer it straight out, but that's a can of worms right there.

Thanks guys!
I think that I'll be able to write my one-shot now, with all the help you've given me.