Lately I've been doing fanfic because I would get ideas of how to develop the characters. Getting their voices down isn't easy I admit, but I'm fortunate to have friends/beta to let me know that. I used to do some original work, but I haven't been able to come up with a new one lately nor inspired to do so. Guess part of it has to do I'm able to get more writing feedback with fanfic than original work (I know there are writing groups, but in my case travel arrangements sometimes isn't easy).
I personally just love to write what many people called "original fanfic". It is still fanfic based on already existing fictions, but instead of adapting everything especially the canon characters and canon story, only the world itself is adapted, or most of the time, adapting only the format, or the core concept.
So instead of writing fics of already existing canon characters such as Ash Ketchum and Misty and Brock and any other companions and TRio, I preferred to write stories of my own original characters. No it is not simply journey fic of original self-insert trainer going on badge quest journey with all the characters we knew already from canon. Every single character is original, and although canon maps is used (because I'm lazy to design my original region), the functioning and principles of the world is original. Especial the story format and tone itself, I wanted to write something that the canon had never done before.
This is it! Yes
That's what I'm doing at the moment. Though, when it comes down to the world building, I prefer to also revamp or expand upon as much as I can, until satisfied. (Also, re-making/re-imagining the Pokémon concepts themselves.)
I'd usually avoid canon characters, but on the very rare chance that one or two of them are too essential to ignore, well, in they go. I'm talking staples like Oak, for example. Characters that are so Pokémon that Pokémon isn't Pokémon enough without them.