How do you get sudowoodu to get out of the way in Pokemon SoulSilver?

After defeating the 3rd Gym Leader, Whitney, you head up northeast of Goldenrod City to find a Flower Shop. When you go inside, talk to one of the women there and she'll give you a SquirtBottle for your victory. Head up to Route 36, then use the SquirtBottle on Sudowoodo to wake it up. It'll be provoked and will attack. Its level is 20 and knows Flail, Low Kick, Rock Throw, and Mimic.