The Helios Sewers connect Helios City to the Black Market. They can be reached through the basement of the Helios Department Store. The area is very dark and may require the player to pick up the Flashlight while navigating the maze.
If the player is having trouble seeing where to go in the sewers, there is a Flashlight located in the room straight up, right, down, and then left from the Helios Department Store entrance.
Navigate through the sewers and enter the Black Market. The quickest way to do this is, starting from the Department Store, go up, left, up, right, up, right, up until the player stands next to a pool of liquid, left, and then up until the player is standing next to the fan which serves as the entrance into the Black Market.
To access the Meloetta tile puzzle, starting from the Department Store, go left, up and then take three consecutive lefts along the wall until the player reaches a pool of liquid, then up until the player is standing next to the fan which leads to the second floor. Rock Smash and Strength are required to reach the puzzle. Note that this puzzle is entirely optional and does not need to be completed in order to continue the player's adventure.
Move Tutor
In the Dead end by the Great Ball in the middle room of the sewer is a man that is willing to teach Gunk Shot and Acid to your pokemon.
Starting from the Black Market: Down, right, southwest in the next room, and then up
Starting from the Black Market: Down, all the way to the right until colliding with a wall, southwest in this new room, and then down (requires Shaymin DNA and Surf)
Starting from the Black Market: Down, all the way to the right until colliding with a wall, southwest in this new room, and then to the right (requires Shaymin DNA and Tesseract)
