I would like to join the club, Dark types are my top favorite type.
Username: Mithel_Celestia
What do you think of Dark-Type Pokemon: most of the Dark type pokemon designs are very cool, the type itself is very mysterious and that is what I love about them.
Your partners: main partner, and battler, A Mightyena going by the name "Karimlan"(which means "darkness" in tagalog.), a second partner, if I have to choose, is a Zoroark, no special name though, but I like it. the moment they introduced it, i knew it was born for greatness XD.
What Types rule: Dark is at the very top, very mischievous and annoys the filling out of others.
Answer the current topic:
Basically, a region's lack of Dark-Type Gyms may be due to some of their move's annoyance and unfairness, if you say it like that, Taunt prevents status moves, Torment restricts the moves used, Payback reaches a base Power of 100, just by falling behind of the others.
That may be one of the reasons Dark type specialist are one of the Elite Four, however, Dark Gyms may be made to be a little easier, just for the the main storyline; or,
It could be made into a post-storyline Gym, no one said that every Regions must only have 8 Gyms, Gary even has 10 badges in the early season of the anime and Barry has some Badges that aren't even in the games.
The Idea of post-storyline Gyms in a game sounds cool and may give someone something to do after defeating the Champion, like HGSS.