New Super Luigi U: Superstar Road-4 -- Hammerswing Hangout

It's time to deal with the swinging hammers again. Go through the pipe and you'll reach an area with the swing hammers. Once you step on the hammer, the level will start automatically scrolling up. The first Star Coin is on the left side, near the Fliprus. You'll have to dodge the snowballs they throw until you can defeat them. In the middle is a Green Ring. Quickly go to the right side, where you'll find the second Star Coin over another Fliprus. Go back to the left wall for the third Star Coin, also over a Fliprus. The pipe at the top will take you to a swinging hammer in front of the flagpole.