When you arrive in Slateport, head straight for the northeast part of town. Outside Slateport Harbor, you find Captain Stern wrapping up a TV interview in front of a small crowd. Afterwards, you catch up with him for a little chat where he informs you of his newest discovery. He's found an underwater cavern on Route 128, and believes it to be the den of a super-ancient Pokémon long though to have been extinct. Just then, you hear a voice booming out from a megaphone. It's MaxieOR/ArchieAS, who mocks the captain and thanks him for the submarine.
After rushing inside the building, you find MaxieOR/ArchieAS standing near the sub, ready to depart. He accepts that you won't simply leave him to his plans, and urges you to visit their hideout in Lilycove City. But he's come too far to be stopped now, and his faithful Admin, TabithaOR/ShellyAS, orders a pair of Grunts to keep you busy while the other two escape in the sub.
Once the battle ends, your friend heads back to Littleroot Town to continue working on her/his Pokédex.
Move Deleter's House
Climb the stairway and visit the first house to the east. This is the home of the Move Deleter, an absent-minded man with the power to make your Pokémon forget any move. This is the only way for a Pokémon to forget an HM move. Unlike the Move Reminder in Fallarbor Town, the Move Deleter's services are free of charge.
Lilycove Department Store
Welcome to the Lilycove Department Store! This massive shopping center offers a wide array of merchandise, so Trainers can find almost any item for sale here.
1F: Service Counter, Lottery Corner
The first floor is a welcome center. The receptionist on the left greets visitors, while the one on the right runs the Pokémon Lottery Corner. Talk to her to draw a random Pokémon Loto Ticket. If the ticket's number matches up with any of your Pokémon's ID numbers, you win a prize! You can draw one Loto Ticket per day.
The fourth floor offers nearly a dozen TMs for sale. Speak to the left clerk to buy TMs for offense, and the right clerk for TMs containing defensive moves.
5F: Decoration Floor
The fifth floor is dedicated to Secret Base fanatics. Here you'll find a wide selection of Decorations to deck out your Base, including dolls, mats, posters, and cushions.
On Saturdays, a major clearance sale is held here. A special selection of Secret Base Decorations are offered, with items listed anywhere from 200 to 6,000.
The Lilycove Museum stands in the northwest part of town. The museum's curator blocks the stairs to the second floor because he hasn't yet decided what sort of exhibit to display upstairs. Once you start winning Master Rank Contests, your Pokémon's portraits will begin appearing on the second floor of the Contest Halls. An artist from the museum will become enamored with these portraits and ask to put them on display here. If you agree, up to 15 of your most recent Pokémon portraits will be displayed: three from each of the five contest conditions. More art fans will visit the museum as you fill its walls with portraits. The curator will be so thankful for the crowds that he will give you a reward after supplying all 15 portraits: a Glass Ornament for your Super-Secret Base.
Near the entrance is a Kindler who offers to sell you one of his modern art pieces. These eye-catching "masterpieces" can be used as Decorations in your base.