After you defeat some Team Galactic Grunts, you can go east to Valley Windworks to rescue the girl's father.
In the grass in front of Valley Windworks, you can catch Bidoof, Buizel, Pachirisu, and Shellos, and you can use the Old Rod in the water to catch Magikarp.
Get a Potion
There is a Potion southeast of the Valley Windworks (if you didn't get it already).
Fight the Grunt
At the door of Valley Windworks, if you didn't already talk to the Grunt there, talk to the Grunt and you will have to do battle with the Grunt's level 11 Glameow. You get 704 Pokédollars for winning.
Unlock the Door
Since you got the Works Key in Floaroma Meadow, you can now unlock the door of the Valley Windworks.
Once inside the Valley Windworks, go to the left, then north, and you can battle a Team Galactic Grunt who has a level 11 Cascoon. You get 704 Pokédollars for winning.
Go east, and you can battle a Team Galactic Grunt at the top of the room who has a level 10 Wurmple and a level 10 Glameow. You get 680 Pokédollars for winning.
The other Grunt to the east is the one that you defeated outside of the Valley Windworks, so you won't do battle if you talk to them.
Go east and talk to the red-head to battle Commander Mars, who has a level 14 Zubat and a level 16 Purugly. You get 1536 Pokédollars for winning.
Now that you have defeated Commander Mars, go outside and go west, then north across the bridge. The Grunts who were blocking the way are gone now, so you can proceed north on Route 205.