Big Boo Battle - Red Coins and Secret Star

This mission is unique to the Nintendo DS.
I started this mission as Mario, entering Big Boo's Haunt on a later mission. (Any mission but the first one will work.)
The first Red Coin is across from the entrance in the carousel. The next two are in the second room. It will take some time to get all of the Red Coins, as some of them will send you on the incorrect path. The next two are in the third room. As Mario, use the Power Flower to get the one floating high in the corner. Two more are in the fourth room. Pick up the Wario cap here. In the fifth room, the entrance to the battle, there is a black brick block with the 8th Red Coin. The Star will appear in the same room, nearby.
Star Get #90, 35 Coins, 6 Lives
I returned later to get the Secret Star. In the room with the entrance to the battle, you'll see a Star on the Touch Screen Map. Despite searching for it, it doesn't seem possible to reach. In the room with the Power Flower, there is a Luigi cap (if you're not Luigi). As Luigi, with the Vanish Cap, run through the rooms, long-jumping to the doors you need to go through. The Vanish Cap does not last long. Run across the fallaway bridge, or long-jump if need be, then jump into the Boo painting. There is a hidden room behind the painting wiht a secret Star.
Star Get #93, 0 Coins, 5 Lives
Just exit the course afterward.
The next Stars are the Red Coins and Secret Star in Chief Chilly Challenge.