Reference article
Ground Smash (Duck Life 9: The Flock)
Use this in a race to make nearby ducks fall over
Obtaining
Talk to 
Atom in 
Toadstool Towers; he introduces Ground Smash and gives you one. To buy more, complete 25 
Mallard Smuggler Tasks for Platy to unlock this item in the Smuggler’s Shop. Buy it for 
100 each.
Using it
Activate it while running to perform a ground slam. When it lands, opponent ducks that are running fall over for four to five seconds. Select its ability button during a race when it is ready. Each activation uses one item from your bag.