>>51147913I think this is the pokemon league, or whatever the location we'll be doing the champion assessment at will be called.
The arena on its roof has a 4 colored border, and the 4 colors are further reinforced with the large ring under the arena. The 4 colors likely representing the elite 4's types in this game.
There is a Pokemon center just outside the building, like classic games, and its at the end of a road the leads out of a cave. The entrance to the cave can actually be seen in the image of the main city.
