you have to beat/capture the Sudowoodo.
You get it at the Flower Shop in Goldenrod City that's right next to the gym.
It's called the Squirtbottle and can be obtained in the Flower Shop next to the gym in Goldenrod City
Buy it from the shop right next to the Goldenrod Gym. Same place where you get the Squirtbottle.
Bill can be found in Goldenrod city next to the underground tunnel. If you are talking about Kanto then it would be in Cerulean cape.
its in goldenrod at next to the poke center (3rd gym)
You have to beat the gym leader and move on to the next city to defeat Goldenrod City.
underneath goldenrod one entence is next to name rater
Go to the flower shop next to the gym in Goldenrod City after beating the 3rd gym leader (Whitney normal type) and talk to the lady
First, beat the Goldenrod Gym leader. Next go to Ecruteak City. There, he is in their Pokemon center. Then go visit his house. He'll give you an Eevee.
After beating Whitney, your next goal is to get to Ecruteak City. To do that, head north until you see a funny tree. Go back to Goldenrod City and ask for the spraybottle in the top right house. You can then get past the tree.
Once you leave the Ilex forest go past the route next to it until you enter Goldenrod city.go to the ixea Forrest or something where you had to get the two farfetch'd and use cut and go up and go around the trees and there are some trainers on the way but you will get there
In Pokémon HeartGold and SoulSilver, you first have to defeat Whitney (the Goldenrod Gym Leader) in a Gym Battle. Next head to the Flower Shop in Goldenrod City and talk to the lady there. She'll give you a SquirtBottle. Take it to the Sudowoodo and use the SquirtBottle on it. It'll challenge you to a battle. Defeat it or catch it and it'll be gone.