A waypoint at the center of an intersection in your journey, Dendemille Town is a wintery little town where you can take a break from your gym challenges. There's not a ton to see in Dendemille Town, but it's nevertheless a place you'll see more than a lot of other towns, assuming you want to check out some optional area. (Which we will.) Shall we have a look around?
  • South of the entrance is the Pokémon Center. A woman inside will give you a Sitrus Berry, and, hey, you probably recognize that pink suit in the corner by now. Mr. Bonding hands over the Accuracy O-Power when you speak to him.
  • Outside the Pokémon Center is a woman who will sell you Moomoo Milk, either one at a time or by the dozen. If you have the money you should stock up, as Moomoo Milk is a good, cheap restorative at this point in the game. Check the bush near the entrance of the Pokémon Center for a hidden Heal Ball.
  • Head back to the Route 15 gate in the north. Beside the stairs to the east of the gate is a house. Inside is a Move Deleter who will permanently remove moves from your Pokémon. This Move Deleter is the only way to remove HM moves from your Pokémon. Also here is a Madam Reminder, who will allow one of your Pokémon - at the price of a Heart Scale - to remember a move they'd forgotten previously. This includes moves which your Pokémon cannot normally learn just by leveling up. Both are invaluable, and you should try to remember where they are for future reference.
  • Go south across the bridge to your right. In a nearby field you'll find a Big Root. Check the middle of the bottom-left field to find a hidden Nugget.
  • Backtrack to the stairs and head north. Ignore the first set of stairs ahead that ascend to the top walkway and head up to the house. A man in here will give you a Shell Bell if you have registered 70 or more Pokémon in the Kalos Mountain Pokedex.
  • Go under the bridge to the left to find another house. Inside is a boy who claims to have seen a huge Gourgeist, but no one will believe him. Show him a Super Size Gourgeist and he'll give you a Big Nugget for proving him right. You'll need to trade for the Gourgeist, as Pumpkaboo doesn't evolve until traded. Outside and to the left of this house is a hidden X Speed.
  • Head south from the previous home to find a third house. A girl in here will give you a Leppa Berry if you show her a TM of her choice. The TM she wants to see is entirely random. The boy in the house will give you TM42 Facade.

That's all for Dendemille Town. At this point you have four potential destinations available to you:
  • The first is the Lost Hotel, located inside the ruins on Route 15, just beyond the outskirts of Dendemille Town. There are trainers, items, and a skating technique to discover inside.
  • The second is Route 16, located south of the Route 15 / Dendemille Town gate, on the Route 15 side. One of the few Routes you can completely skip, Route 16 will take you back to Lumiose City, and helps you pick up one important item that's technically on Route 15. Despite being optional you should run through Route 16 at least once.
  • Your final option is the Frost Cavern, located across the northbound bridge beside the namesake windmill in Dendemille Town. You'll have to head here eventually, so we'll save it for last. If you just want to get through the game, however, you can head here first and skip the Lost Hotel and Route 16.
  • (Technically you can also head to Route 17, via the gate in the southeast of Dendemille Town, but you need to check out the Frost Cavern first before you can continue west through Kalos.)
Where you go is up to you. For the sake of being thorough, we'll check out the Lost Hotel first.