Go up the steps next to the Pokemon Center to get to the train station.
You'll bump into an old lady who'll give you TM89 U-Turn.
At the end of the platform, you'll find a Rare Candy.
Go to the wooden cabin south of the Pokemon Center. Show the girl inside a Pokemon
with the move Nuzzle and she'll give you a Revive. The bush right by
the cabin has a hidden Pretty Wing.
Before crossing the bridge south of the city, Professor Sycamore will come by
to challenge you to a battle! Sycamore uses
a Lv. 50 Venusaur,
Lv. 50 Charizard, and
Lv. 50 Blastoise.
If you have a well-balanced team, this shouldn't be much of a problem.
Afterwards, cross the bridge.
Go inside the first house you see. A girl inside will ask you a couple questions
about your starter Pokemon and, if you get them right, you'll get either a
Mystic Water, Miracle Seed, or Charcoal.
Head up the steps eastward to find Couriway Hotel. Inside, on the right side
of the lobby, a little boy will give you TM55 Scald for correctly answering his question.
Upstairs, Mr. Bonding will give you the Stealth Power Lv. 1 O-Power.
The guy standing outside the hotel sells Fresh Water for $300 a pop.
If you buy one from him, he'll throw in a free Oran Berry.
Pick up the Max Potion by the waterfalls.
Now, continue south onto Route 19.
Next to the first trainer you encounter is a hidden Net Ball on the rock.
Head east to battle a Sky Trainer. In the southern corner is a hidden Antidote.
Head west. Hop to the center island to pick up a Max Revive.
Before you cross the bridge, go through the flower field to pick up an HP Up.
If you feel like it, there's an optional area you can explore if you follow the
steps down near the first trainer. Here, you'll find a Rare Bone,
Yache Berry, Toxic Plate, PP Up, and TM36 Sludege Bomb.
Cross the bridge. Shauna will come by to battle you. Afterwards, Trevor and Tierno
will come by and battle you too! Afterwards, Shauna will give you HM05 Waterfall.
Continue across the bridge.
Pick up the Timer Ball hidden in the top-right corner of the flower field.
Now head west into Snowbelle City for your final gym badge.