I'm all about original regions. There's a lot you can do with it because then you can introduce everything yourself. It is a lot harder to write, though, because you can't rely on your readers having pre-conceived ideas of where things are and what characters look like. So since you admit that description is your weak point, doing an original region would be an EXCELLENT exercise/challenge for you. It would really force you to bring the new world to life. Just don't look at it as "I stink at description so I won't be good at this", look at it as "This will be a project to really push me!"
You could say the same thing about original pokemon, too, but...eh. I'm not a big fan of those. Creating regions and gym leaders and cities and cultures is a lot of fun to read, but creating pokemon is the line for me. Not that I think it's unacceptable by any means, it just doesn't personally interest me.
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