Finished all of the challenges for the new courses. Some of them are completely ridiculous.
For example, for one of the Moon Coin challenges in Layer-Cake Desert, you need to grab the coin that is directly over an out-of-bounds field, facing away from the course. To do this, you need to grab the music block power-up, then shoot the ball with the power-up in a way that the music block will bounce your ball into the coin, grab it, then deflect off of a ledge overhead so that it will travel backwards and land in an non-out-of-bounds area. It's insane.
Another dumb one was one of the Sparkling Waters Moon Coin challenges. For this one, you need to land on a small island near the beginning, then Bullet Bill over to the island near the green while grabbing the Firework... thing (what is that called, anyways?). Then you need to use the Firework power-up to grab the Moon Coin high up on a mountain directly behind the green, but you need to also make sure to hit the wall behind the coin or else you'll be out-of-bounds (so simply falling into the coin won't work; trust me, I tried). THEN you can finally use your last two strokes to aim for the hole. However, the window you have for the Bullet Bill shot is ridiculously small. When landing on the first island, you need to make sure you land on the far left edge of the fairway. If you land in the rough, you won't have enough power to reach the second island (even with Star Bowser). If you land just a tiny bit to the right, you won't even have a clear shot for the second island because the cliffs on both sides will be blocking the path. Good luck landing in this little spot with the strong wind, by the way.
And for the love of all that's good, don't miss the putt!