Floaroma Town is a peaceful town known for its flowers. Heal your Pokémon at the Pokémon Center. You'll notice two Team Galactic Grunts blocking the path to the east. Talk to the man near the flowers, and he'll tell you about the Grunts stealing honey. Head east to the Valley Windworks.
At the Valley Windworks, you'll find more Team Galactic Grunts. Battle the grunt outside, then enter the building. Inside, you'll face two more grunts and Commander Mars, the first Team Galactic Commander. Her Purugly is a formidable opponent, so be prepared. After defeating Mars, Team Galactic will retreat, and you'll receive TM94 (Rock Smash) if you haven't already.
Now you can head north from Floaroma Town onto Route 205.