Pokémon Ruby and Sapphire/Mossdeep City

Mossdeep City is the easternmost City in Hoenn (discounting Ever Grande city), and the only city in the region completely surrounded by water. It houses multiple places of interest, including the 7th Gym.

Mossdeep Space Center
Mossdeep Space Center is a massive launch facility for rockets, located on Mossdeep's highest point. A Sun Stone can be obtained from a sailor on the first floor.

In Pokémon Ruby and Sapphire, the center has no other value beyond the Sun Stone, in Emerald, it is the site of a major battle between the player and Team Magma (see the section "after the gym" for details).

Steven's House
Thanks to the nearby cave having the potential to hold rare stones, Steven Stone has decided to make Mossdeep his home. He keeps a part of his extensive rock collection here, and is more than welcome for you to take a look.

In Pokémon Ruby and Sapphire, he gives the player HM08, but it cannot be used outside of battle until you defeat Mossdeep's gym.

The Secret Base Boy
The house west of the Pokémon Center has a brother and sister inside. The boy likes visiting Secret Bases, and will tell you where your Secret Base is (if you have one).

Pokéblock Enthusiast
Just north of the Pokémon Center, a man can be found who will tell the player the preferred color of Pokéblock for their lead Pokémon.

Backdoor House
This one is specific to Pokémon Ruby and Sapphire. In one of the houses, an old man and a door can be found. Going through the door will lead you to the room where e-Reader trainers appear.

Game Corner
In Pokémon Emerald only, a game corner can be found instead of the Backdoor House. It provides the ability for player of Pokémon Emerald to interact with other people from Pokémon FireRed and LeafGreen and other copies of Emerald in two mini-games. This requires the Game Boy Advance Wireless Adaptor.

Flying Errands
Visiting the house nearest to the launch facility's staircase will result in meeting a young woman and her. Talking to the Wingull will cause it to fly off, towards ../Fortree City/. Returning to Fortree and talking to the Pokémon Breeder in the northeast house will result in a being given to to player.

Move Tutor
In Pokémon Emerald, there is a man on the western shore of the city, who will teach a compatible Pokémon the move. This is a one-time opportunity, so pick wisely!

Items Found

 * - In the southeast corner of the city.
 * - Obtained from a boy outside Steven's house.
 * HM08 - Obtained from Steven, in his house (Ruby & Sapphire); Obtained from Steven in his house after defeating Team Magma (Emerald)
 * - Received from the Fisherman in the house east of the Gym.

Mossdeep Gym
Mossdeep Gym is the 7th Gym in Hoenn, and one of the few obstacles remaining in your path to becoming the Champion! It's theme is psychic Pokémon, and consists of a maze of conveyor belts (Ruby & Sapphire)/teleporters (Emerald).

The gym is also the only one in the region to have two Gym leaders. They're the twin psychics, Tate & Liza.

Tate & Liza in Ruby & Sapphire
If you picked as your starter, then Tate & Liza are hilariously easy. Lunatone and Solrock are both Rock/Psychic type, which means that they are both weak to Water type moves. Considering how far into the game you are, your Mudkip should now be a Swampert, and can easily one-shot both of them with moves like, , and.

If you didn't pick Mudkip, then the weakness above still applies, but it may be slightly more difficult to take them down. Emphasis on slightly.

Lunatone is level 42 and has the ability, which prevents Ground-type moves and arena traps from hitting it. For moves, it has to raise its Sp.Def for 5 turns,  to deal STAB damage,  to put your Pokémon to sleep, and  to sharply raise its Sp.Atk.

Solrock is also level 42, and also hold the ability Levitate. Its moves are to make the arena Sunny,  to take advantage of the now-sunny arena,  for STAB, and  to once again take advantage of it being sunny.

Tate & Liza also have 4, which will most likely heal their Pokémon to full health every time.

Tate & Liza in Emerald
In Pokémon Emerald, the twins have a significantly better team, adding and  to their roster. Lunatone and Solrock remain exactly the same, except they now both hold a too.

Claydol is a level 41 Ground/Psychic type. Its ability, like Lunatone and Solrock, is Levitate, which prevents Ground-type moves and arena traps from hitting them. Claydol's moves are to deal an incredibly high amount of STAB damage,  to annoy you,  for more STAB, and  to raise its Sp.Def for 5 turns.

Xatu is a level 41 Psychic/Flying type, and has the ability, which applies any status condition its afflicted with to the player's Pokémon. For moves, it has for STAB,  to aid Solrock,  to confuse your Pokémon, and  to raise its Sp.Atk.

Defeating Tate & Liza awards you with the, the ability to use outside of battles, and

Battle Team Magma at the Space Center
This part is from an Emerald play through. It may be different in R&S.

F2
Immediately when you go upstairs you're surrounded by three gunts. These three trainers are back to back to back, no pauses in between. Thankfully it's only one Pokemon to beat per fight.

Once you go further in you'll team up with Steven himself against Leader Maxie and Admin Tabitha. Pick your three strongest to take them on!

Maxie starts to rethink his actions on being misguided, wondering if Archie is also misguided in his thoughts. Steven invites you to his house here on the island! Make sure to swing by for HM 08 Dive!