What's the pitch and one putt thing in the Castle? It's at the top right of the whole place.
I think you need to do it to unlock Sky Island. Well worth the effort, though, just for the satisfaction alone. And you get another 10 levels in Star Coins mode if you do unlock the course.
If you all don't mind having me, I'm up for joining in the tourneys at some point.
I forgot to mention this, haven't had a chance to confirm it yet so it might be misinformation.
I don't think you need to unlock the courses with star coins to join private tournaments. I thought I had the required 28 coins, took part in the Donkey Kong tourney, but I didn't unlock the course in single player until a couple of days ago. So if anyone's as green as me, but held off taking part 'cos they've got nothing unlocked, you may or may not be OK to join anyway. You just can't knock this kind of useful info.
Hang on a sec, is this supposed to be Yoshi Lake? I might have played the wrong tournament. It started with a desert and the floating bouncy platforms.