This mission is unique to the Nintendo DS.
Now that we have Wario, we can gather all of the Red Coins in this course. I started the course as Mario. After moving past the rising stumps, taking poison damage on the way, we come across a platform moving over the abyss to a stump with a black brick block. On the stump is a Goomba with a Wario cap. After getting the cap, we break the block to reveal a Red Coin. When we return to the main part of the course, there is a grate spanning a gap over the poison. We can hang onto this grate, and there is a Red Coin underneath it that we can grab while crossing the gap. There is a Piranha Plant at the end, so be careful. I lost the Wario cap to it. Unfortunately, I fell in the poison gas too many times.
Take 2- I got the Red Coin under the grate and fell into the abyss trying to reach the one in the black brick block.
Take 3- I got 2 Red Coins and fell into the abyss.
Take 4- I got a 1-up from on top of the grate and got the Red Coin underneath it. I got the brick block Red Coin and jumped accidently into the abyss.
Take 5- I got the first two Red Coins, plus a couple of 1-ups. There is another Red Coin on the main level above a rising stump, near the entrance to where you battle Goomboss. I let a Goomba run into me to get rid of the Wario cap. Near the rising stump is the blue Star where you'll find the Star when it appears. Behind it is a series of rising stumps; the last of which is under a Red Coin. That stump doesn't move, but it has a Piranha Plant resting on it. Nearby is a tilting square platform with another Red Coin. Going back to the vine you climbed to reach Goomboss, at the top on the small branch is another Red Coin. Near the Switch Star area is a very tall stump. There is a Goomba wearing a Luigi cap there. We put on the cap and cross the abyss using tilting square platforms. There we will find a Power Flower. We quickly run back to the tree and backflip to a cage. We pass through the grate to find the next Red Coin. There is a Power Flower in the cage in case it runs out before you leave. After letting a Goomba hit us to get rid of the Luigi cap, we go back to the area with the Power Flower. Using it as Mario, we float up to the top of the same stump to find the last Red Coin. We jump down from the stump and get the Star.
Star Get #89, 42 Coins, 4 Lives
All we have to do is exit the level. If you're wondering what's on that far ledge, there is a 1-up on the far ledge of the tall stump with the cage.
The next Stars are the Red Coins and Secret Star in Big Boo Battle.