The hut on the beach's west side is known as the Seashore House, where refreshments are sold to thirsty beachgoers. Defeat all five Trainers inside, then speak to the proprietor at the counter. He rewards your effort with a free six-pack of Soda Pop! From this point on, you can also buy individual bottles at 300 apiece.
The open-air market hosts numerous vendors peddling rare goods. A man near the southern entrance hints that you'll find even more bargains after obtaining TM94 (Secret Power). Permanent stat-boosting Vitamins can be purchased from the Energy Guru. The red-clad clerk standing next to him will give your lead Pokémon an Effort Ribbon if it has been well-trained. Incense and TMs are also available from other vendors.
Pokémon Fan Club
The Pokémon Fan Club can be found just north of the Market. Speak to Gabby, the reporter, to tell her about your lead Pokémon. Give her and her cameraman a great interview and you may see yourself on the BuzzNav news! If your lead Pokémon is friendly enough toward you, you can receive a Soothe Bell from the woman near the back wall. Visit with the club's chairman to have him examine your lead Pokémon's condition. If any of its five Contest stats are high enough, he will reward you with a special item—a Red, Blue, Pink, Green, or Yellow Scarf. When held, these items boost their respective stat during the Appeal Round of a Contest Spectacular.
In addition, there is a Breeder here who offers to groom a certain Pokémon. For 500, she will trim the coat of a Furfrou, a Pokémon that is not native to the Hoenn region. Its coat will grow back in five days, or whenever it is deposited in the PC.
North of the Fan Club building is the home of the Name Rater. This man has the power to evaluate and change your Pokémon's nicknames as often as you'd like. However, he cannot change a Pokémon's nickname if it first belonged to someone else.
The Harbor is located in the city's northeast district. Since construction is not yet complete on the new ferry, there is little to do here aside from stopping by the Vending Machine for Soda Pop.
Inside Stern's Shipyard, you find the captain's assistant, Dock, looking over plans for the new ferry that is under construction here. Stern is nowhere to be found, but Dock hints that he likes to visit the Oceanic Museum.
At first, it is impossible to enter the Oceanic Museum because of the Team MagmaOR/Team AquaAS Grunts lined up outside. But by the time you visit the shipyard, the group has made its way into the building. Pay the 50 entrance fee to follow them inside. Those that can't afford it will be mistaken as part of "the group that came in earlier", and allowed in for free.
The Grunts are more interested in the exhibits than battling with you, so speak to them in an effort to gauge their intentions. Talk to the Grunt in the lower-right corner to give him a shock; it's the same guy you fought back in Rusturf Tunnel! He's learned not to mess with you, and begs forgiveness with TM46 (Thief) before fleeing the scene.
Go upstairs to find Captain Stern, examining a display in the lower-right corner. Before you can hand over the Devon Parts for his new ferry, you are attacked by two Grunts! Defeat one after the other to save the captain and complete the delivery for Mr. Stone. Shocked at their failure, the two begin to plan their next move when a stranger appears. It's their boss, Magma LeaderMaxieOR/Aqua LeaderArchieAS! He seems impressed by the fire in your eyes. He explains his group's goal and departs, but not before warning against interfering with their future plans.
With the Devon Parts delivered, you're all done in Slateport. As you try to leave through the city's north exit, you are drawn to the excitement of a video shoot outside the Contest Spectacular Hall. A girl named Lisia is being filmed with her Altaria, Ali, and the frenzied crowd can't wait to see who she picks to debut in the Contest Spectaculars. It happens to be your lucky day, as she hands you a Contest Pass and a Pokéblock Kit, everything you need to get started in the "wild world of contesting"! Each new entrant starts off in a Normal Rank Contest; win, and the next, more prestigious rank is unlocked. Work your way up to a Master Rank Contest, and your win earns a special Ribbon your Pokémon can wear with pride. Collect all five with a single Pokémon to receive the rare Contest Star Ribbon!
When the shoot is over, follow Lisia inside. Approach the counter and she calls out to you. She is thrilled that you are ready to try a Contest, but has one more gift for you first. She leads you into the dressing room where she gives you a Contest Costume to wear during the show.
Once your first Contest is over, an inspired Breeder gives you a special female Pikachu. This Cosplay Pikachu loves dressing up for Contests, and starts out in either its Rock Star or Pop Star outfit. This Breeder loves to make costumes for it, and will set up in the dressing room to change its outfit whenever you like. Each of its five costumes is best suited for a certain Contest condition, and even lets Pikachu learn a new move that matches its costume.
The Trick House is located farther north, near the Route 103 junction. The building's owner, the Trick Master, is a fun-loving prankster who has crafted many entertaining tricks for travelers. Don't let his hard work go to waste!
When you step inside, you can't shake the feeling that someone is watching you. The mischievous Trick Master is hiding somewhere! Search the entire room until you find him, when he accepts your challenge and disappears. Certain field moves are required for most of the mazes, so you will need to return later to complete the rest.
Inside the Maze
Once he leaves, examine the scroll on the wall to find a secret passage that leads to a devious maze. Navigate the maze and battle Trainers as you search for a rolled-up scroll with a secret code. Reach the back of the maze and examine the hanging scroll. Inscribe the code on the hidden door to open it. There's no going back, so be sure to find everything the maze has to offer before entering the next room!
Trick Master's Room
The Trick Master waits here for all challengers. Speak to him to receive your reward, then leave through the exit in the north wall. After the last challenge, you should visit once more to say goodbye to one of his Mechadolls, and check his scroll too.
Rival Battle 2
Go east from the Trick House and pass beneath Cycling Road. Turn north and continue on until you meet May/Brendan again. It seems like ages since you last met, and your friend wants to see how far you've come as a Trainer!
May/Brendan is kind enough to heal your Pokémon after the battle. She/He then hands you the Dowsing Machine, a special gadget that allows you to search the surrounding area more thoroughly to discover hidden items! However, it can't detect an item if you are standing on it. When equipped, the machine emits different noises and the lights change color depending on how close you are to an item. When the lights turn red and the noises go wild, there's an item right in front of you! Search the underpass for treasure as you continue on to Mauville City.
Route 103 (East)
You can also explore the previously unreachable Eastern side of Route 103. Battling a few trainers can provide some extra experience points before reaching Mauville City.