After you defeat Roxanne and get the Stone Badge, you have to retrieve the Goods that the Team Magma/Aqua Grunt stole.
In Route 116, you can find Taillow, Nincada, Whismur, and (rarely) Skitty. In addition, in Ruby and Sapphire you can find Zigzagoon, and in Emerald you can find Abra and Poochyena.
You should go east through the route. There are two patches of grass near where you first enter the route. Go into the northern patch of grass. Youngster Joey is there. In Ruby and Sapphire, he has a level 8 Zigzagoon and a level 10 Machop. In Emerald, he has a level 9 Machop.
Now go into the southern patch of grass to find a Repel. Near the Repel, there is Bug Catcher Jose. In Ruby and Sapphire, he has a level 8 Wurmple, level 8 Silcoon, and level 8 Nincada. In Emerald, he just has a level 8 Wurmple and a level 8 Silcoon.
Continue going east and you find more grass. On the left side of the grass, you find Lass Janice. She has a level 10 Marill. In Emerald, she might do a Double Battle with School Kid Jerry depending on where you are standing when they see you.
At the right side of the grass, there is Hiker Clark. In Ruby and Sapphire, he has three level 8 Geodudes. In Emerald, he has one level 8 Geodude.
East of there, you find the Tunneler's Rest House. To the left of that house, there is an area that you can go through if you have Cut. You can find various items in that area, such as an Ether, Potion (Emerald only), a hidden Super Potion, and some Chesto and Pinap berries. You can also battle School Kid Jerry, who has a level 9/10 Ralts, and School Kid Karen, who has a level 9 Shroomish, and (in Ruby/Sapphire only) also a level 9 Whismur.
Go east from this area. There is an old man who says a thug stole his Peeko. Go east and up the stairs to find an X Special.
Now go into the cave next to where the old man is standing. This is Rusturf Tunnel.