Captain Toad finds himself in the Sprixie Kingdom, where there are no gems. As he can't jump, there are some places that are out of reach. You can touch the blocks on the GamePad to break them or get items from them. There are some invisible coins here. Go up the hill and past the Goombas to reach the clear pipe cannon to the next area. Go to where the Cat Goombas are and break the crates. One of them has a 1-up. On the bridge, towards the back is a ladder to the area below the bridge. Here you'll find a Gold Mushroom. Use the Warp Box to return. Take the clear pipe up to the next area. Get the Green Star at the end to clear the level.
Special Challenge: Collect the Gold Mushroom.