Setting
Once they've acquired the Rumble Badge against Korrina's fighting-types, then they will be allowed to ascend the Tower and learn the secrets of what is known as Mega Evolution, allowing Trainer and Pokémon to draw power from their bonds in a unique way that actually begets a temporary power-up and transformation. Only certain Pokémon in their final evolutionary state can benefit from such a transformation, however.
That's not to say that's all the town is good for. The standard amenities are present, and the Poké Mart even sells some useful TMs like Dig and Poison Jab. Even the Surf HM can be found around here if you know where to look, as well as some Berries that can be found by Trainers that are savvy enough to manipulate their environment during a battle with a wild Pokémon.