The Sugline Cave is located in the east of the desert.
Inside the cave, there are many sand pitfalls that either take you to the floor below, or back to the entrance. The middle-most pitfall on the first floor of the cave takes you to a raised stairway that the player cannot cross. In order to lower the staircase and progress to the Sugiline Ruins, the player must press two buttons on Arceus statues that are on both sides of the staircase- these must be accessed through the other pitfalls in the cave. There are a variety of items to collect through the many pitfalls, such as elemental seeds, etc, though collecting them is not necessary to progress.
If the player is travelling with Taka, he shares some insight on the history of this cave, mentioning how it was once home to his ancestors. As the player and Taka progress through the cave, he remembers more and more about going to the cave as a child with his father, Solaris.
The entrance to the Sugiline Ruins is located north of the staircase. Inside, there are multiple garchomp statues that will come to life battle the player if they are run into. Taka explains how the garchomp statues were set up as a trail by his ancestors to guard the inner ruins.
Past the entrance is the Sugiline Ruins, an open area with debris many hidden items scattered about, the ruins of Taka's ancestors' long-gone settlement. At the back of the room, the player will find TM Stone Edge, a healing star, as well as an Arceus statue. If the player interacts with the statue, the sand pits will open up, leading way to a second part of the ruin.
Due to the fact that encounter rates will always change depending on where an oasis is located at (there are 4 possible locations), most rates will be ??? unless a pokemon will always appear at a specific encounter rate