You may find Olivine City by going past Ecruteak. On the way, there will be a Green Apricorn, and a few Trainers willing to battle you. Also, you will find the Miltank Farm, which sells Moo Moo Milk, fresh from the Miltanks they have. There, you can buy a single bottle, or buy a dozen (12) at a time.
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It is in Olivine City, in the restaurant next to the Pokémon center. A sailor will give it to you.
It's the last building to the far right, In front of the water in Olivine city
Take the SS Aqua to go to Olivine City.
in olivine city
In olivine city.
surf from olivine city
at olivine city
Olivine city
Olivine city
The Lighthouse is in Olivine City.
olivine city