When you first enter here, you might think that it's snowing, but it's not. It's actually ash that's falling from the sky... Don't worry, it's not going to do anything to you or your Pokémon.
Also on this route, there is a house that serves as a Factory for multiple flutes, each with different effects, depending on the flute. You are able to get all these flutes for free...but there's a catch. In order to create the flutes, you'll need to walk a certain amount of steps in the soot-covered grass, once you get the "Soot Sack", but we'll talk more about it later.
Inside the shop, the owner will give you a Soot Sack. The idea is to walk around in ash to get adequate soot. To get it, go through the gray grass, turning it green. Grab the required amount of soot to get these things:
Blue Flute (awakens sleeping Pokémon): 250 Steps
Yellow Flute (snaps Pokémon out of confusion): 500 Steps
Red Flute (snaps Pokémon out of attraction): 500 Steps
White Flute (lures wild Pokémon): 1000 Steps
Black Flute (keeps away wild Pokémon): 1000 Steps
Pretty Chair: 6000 Steps
Pretty Desk: 8000 Steps
Items
Ether - In a pile on the eastern-most ledge (Hidden)
Super Repel - On the eastern-most ledge
TM32 (Double Team) - In an ash pile north of Youngster Dillon, near Fallarbor Town (Hidden)
Max Ether - Third ledge from the east, north of Parasol Lady Madeline
Nugget (Emerald only) - On the first ledge from the east (Hidden)
Hyper Potion (Emerald only) - At the edge of the soot by the soft soil patches, to the south near the trees
Sandshrew
Skarmory
Spinda
Slugma
Trapinch (lvl. 18) 
Linoone (lvl. 20)
320
Koffing (lvl. 17) 
Numel (lvl. 20)
Whismur (lvl. 20) 
Nincada (lvl. 19) 
Ninjask (lvl. 19)
Aron (lvl. 20)
Baltoy (lvl. 18) 
Marill (lvl. 17) 
Lombre (lvl. 19)
Swellow (lvl. 19)