Deep inside the woods, you come across a researcher from Devon Corporation, a company based in Rustboro City. After explaining that he is looking for a Shroomish, he is suddenly confronted by a member of Team Aqua. The thug had planned to ambush the worker when he left the woods, but grew too impatient for that. Defeat him in battle and he flees the scene, but not before hinting that his friends are up to something in Rustboro. The grateful researcher gives you a Great Ball as thanks. He then heals your Pokémon, and rushes off to Rustboro after realizing what his attacker wanted.
The Pretty Petal Flower Shop is run by three sisters. The eldest sister teaches all visitors how to grow Berries. The middle sister hands out the Wailmer Pail when you first speak to her. The youngest sister will hand out one random Berry from a group of eight every day.
Stop by the Cutter's house next to the Pokémon Center. When the city was expanding, he taught his Pokémon a move to help clear the surrounding land of trees. He no longer needs his HM01 (Cut), and gives it to you. In the field, Cut may be used to clear away small trees and tall grass.
Devon Corporation is headquartered in a large stone building in the northwest part of town. The company is responsible for manufacturing many of the items Trainers rely on every day, including several variations of Poké Ball and medicine. Only authorized personnel are allowed past the first floor.
Pokémon Trainers' School
The Pokémon Trainers' School stands to the northeast of the Pokémon Center. Talk with the teacher to receive a Quick Claw, and brush up on the basics by reading the notes on the blackboard.
Just inside the entrance, you find the Man in Sunglasses again, who introduces himself as Scott. He's been searching everywhere for outstanding Trainers, specifically Pokémon battle experts. He wonders what brings you here to school, and claims that the first thing you should do as a new Trainer is teach Cut to one of your Pokémon. It's a useful field move, but using it outside of battle requires the badge from the local Gym.
Time for a Trade
The Rustboro Gym beckons, but before you step inside, visit the house to the east. Inside is a boy who is looking to trade his Seedot for a Ralts. Seedot is a Grass Pokémon that eventually evolves into a Grass/Dark Pokémon, Shiftry. This one is even holding a Chesto Berry to sweeten the deal.
Rustboro City Pokémon Gym
Leader: Roxanne The Rock-loving honor student!
After the battle, Roxanne awards you the Stone Badge, which boosts your Pokémon's Attack by 10% and enables the use of Cut in the field. She also gives you TM39 (Rock Tomb) as a prize.
When you leave the Gym, you witness a Team Aqua Grunt escaping from the Devon Corporation building. That same Devon researcher from earlier is close behind, and chases the thief northward. He loses track of him in the northeast, where the city connects to Route 116.
When you reach the entrance to Rusturf Tunnel, you find old Mr. Briney standing there. It seems that the thief has added kidnapping to his list of charges, as he has also made off with Mr. Briney's beloved Wingull, Peeko!
The tunnel is fairly small, so you will find the thief and his hostage shortly after you step inside. Defeat him, and he gives up the Devon Goods before fleeing. The old man rushes in to check on his Peeko, and introduces himself as Mr. Briney before the pair leaves for his cottage near Petalburg Woods.
Now that you have reclaimed the Devon Goods, head back to the Devon Corporation building in Rustboro's northwest corner. The grateful Devon researcher is waiting on the city's east side, and hands you a Great Ball before escorting you inside to meet his boss.
On the third floor, the company president introduces himself as Mr. Stone. He thanks you for reclaiming the stolen parts, then asks for another favor. He doesn't expect you to work for free, of course, and rewards you with your very own PokéNav! In return, he asks that you deliver a Letter to a man named Steven in Dewford Town. To reach Dewford, you will need to cross the sea, so Mr. Stone suggests booking passage with Mr. Briney, the friendly old sailor from Route 104.
As you leave, take note of the Scientists on the second floor. None of them are having much luck with their projects, except one, who has developed a device that can resurrect ancient Pokémon from Fossils.
The PokéNav is a small, electronic device produced by Devon Corporation under the orders of Mr. Stone, who wanted a way to keep track of a Pokémon's feelings. It has four different functions, though only Map and Condition are available at first.
The Map page displays a map of Hoenn, along with the user's current location. It's also possible to zoom in to see a basic layout of towns and cities.
The Condition page shows a Pokémon's five Contest stats in detail. It can be used to search for party Pokémon, or all owned Pokémon at once.
The Match Call function records data of up to 85 people, including non-Trainers like Mom and Professor Birch, and allows the user to call anyone who has registered their PokéNav with the user. This will also alert the user when any registered Trainer, including Gym Leaders, want a rematch. Only the first four rematches with each Trainer will see their Pokémon rise in level and evolve, though there is no limit on the number of times these Trainers may be rebattled. After entering the Hall of Fame, each Gym Leader will offer a rematch as a Double Battle.
There are several people whom you have already encountered, that you must seek out and speak with in order to register them:
The Ribbons page displays all Ribbons the user's Pokémon have acquired. Though hidden initially, this function unlocks when any of the user's Pokémon gains a Ribbon.
When you leave the building, you are stopped by one of the Devon Scientists. He adds the Match Call function to your new PokéNav, and asks that you call Mr. Stone as a tutorial.
Rival Battle 2
May/Brendan is waiting for you just outside the Poké Mart. She/He notices the Match Call feature on your new PokéNav, and each Trainer registers the other. Your friend mentions passing Mr. Briney in Petalburg Woods, before asking about your Pokédex and challenging you to a battle.