Boos' 8 Red Coins

This Star is unique to the Nintendo DS.
We return to the courtyard to get the Red Coins from the Boos. We can't use Yoshi, because he can't defeat Boos. If he eats one, he gets a message saying "You...can't...EAT... ghosts! Eee hee hee!" He will then spit the Boo out. He can't even ground-pound them. One of the nearby signs says "Pssst! The Boos are super shy. If you look them in the eyes, they fade away. They reappear when you turn your back, so don't let them sneak up on you! It's no use trying to hit them when they're fading away. Instead, sneak up from behind and punch them. You can't swallow Boos, so this is where you'll need a mustached hero to save the day."
So we'll use Mario. We take a hit from a Boo, then ground-pound it to get its Red Coin. Not all Boos have Red Coins, so you can just look for the ones with Red Coins or just attack any and all of them. Just ignore the Big Boo for now. He doesn't have any coins. We take 5 hits from the Boos and get all 8 Red Coins, listening to them scream. The Star appears in the back of the courtyard.
Star Get #37, 19 Coins, 4 Lives
The next Star is Go on a Ghost Hunt.