I know I said something about this before, but it got shut down for having not enough information.

I think PU should have a battle frontier, and take some facilities from the Emerald one, and the three introduced in HGSS.  We could also create new facilities.  Here are some examples.

The Battle Cone: Basically you have ten floors, and for each floor there is a circle that spins.
Each circle has three trainers, and an empty square.  The trainers face outward, and when the circle stops spinning, either you are challenged by one of the three trainers or the square stops in front of you and you get to skip that floor.

After you complete the tower 3 times, you are challenged by a brain and get a silver symbol
After you've completed it 7 times, (harder now cuz there are 4 trainers and a square instead of 3) you get a gold symbol.

That's an idea for one facility.  The PU modsare smart, so I'm sure we could have an awesome battle frontier.