Route 113
The center looks normal even as you get closer, other than the door being partly open, and the pokeball symbol above it flickering weirdly. Jake quickly finds a way closer where you won't be seen from the windows, letting you creep up to the building.
Looking inside, the signs of a fight are much more obvious. Some of the lights have blown out, the walls are marked by burns, and a Team Gaia grunt is standing behind a bench, a Magneton floating above him, emitting barely visible waves of energy.
In one of the corner, another grunt and her Nidorina are keeping watch over a scared Nurse Joy and her injured Chansey. And though you can't see much through the opened back door, you see enough moving shadows to guess someone else is there, making a mess.
From what you can tell, there's half-a-dozen windows, and two doors that would let you get inside. The partly opened (and watched) front door, and the closed back door.