Instructions
Follow Route 44 until you reach the cave and then enter. Walk to the right and then continue upwards to reach the first section of ice. Slide across and then go up the stairs on the other side.
Continue along the path until you reach the steps and then walk down them. Walk to the left and you'll reach the next section of ice. Slide up, left, up, left and then down, left and up. A rock on the floor will stop your sliding each time and allow you to slide in a new direction.
Slide to the right to get off the ice and reach the next section. Walk up the steps and speak to the man to find out that he lost his Pokeball. You will see it directly below him on the ice path.
Walk left and go down the steps and then walk right to get onto the ice. Slide up when your character comes to a stop and slide up again. Continue left and then down before going left again.
Slide up and then finally slide to the right. Your character will come to a stop right in front of the Pokeball. Press the "A" button to pick it up and then slide back to the left.
Go down and then left to get off the ice. Go up the steps, walk right and speak to the man again. He will thank you and allow you to keep the Pokeball you just picked up. It contains "HM07, Waterfall."