Guys, I was just looking at these images:
Just a normal image which basically revealed Poké Marts, right? Well, I have evidence that this is
Petalburg City and May and Brendan are on Route 102.
Recall that we've already seen Pokémon Centers and what I (we?) believe to be a gym:
I've circled some stuff on the second image of the Beautifly to show that the placement corresponds with how Petalburg City is arranged
Now take a look at the original map of Petalburg:
If anything, the house and Gym are close to each other like original Petalburg. The house design in the second Beautifly image kind of looks like a revamped Petalburg house (to me at least.) From this, I believe May and Brendan are on Route 102 and are near Petalburg.
I may be wrong, but I just wanted to show this off. Sorry if it gets hard to follow. xD;