I played against a R.O.B. player this afternoon in a Worldwide match. He beat me on Luigi's Mansion (by a hair), and then I beat him on Delfino Plaza (with the help of triple mushrooms right at the last turn). Ok, the thing is, he had picked Sky Garden for the second match (I picked Delfino). So he chooses Sky Garden for the 3rd race and I choose it as well to be nice.
All is going well, I'm right behind him for the whole first lap, then all of the sudden he disappears into the clouds. I started laughing b/c I thought he had fallen off and then he suddenly appears in front of me. Ok, so I started to get suspicious and got caught back up with him on the 2nd lap. Sure enough, he flies into the clouds again and ends up ahead of me. So the third lap, I decide I'm going to follow exactly what he does. He does the same thing except I fall into space and he keeps right on trucking.
Apparently, there is a nifty shortcut on Sky Garden about 3/4 of the way through the track. Just as the track is making a right-hand turn, there is a group of clouds straight in front of you that you can "hop" across and cut an entire corner of the track out. I didn't realize he was jumping them, I thought he was using some glitch where Lakitu put him further ahead of me.
So of course on the 4th race he picks Sky Garden again, and it manages to get picked. I still didn't know the trick so he smoked me again. It's pretty lame to pick the same track 3 times in a row on the chance that some MK noob (like me) will not know the shortcut and you can rack up easy wins.
Just a heads up to others that don't know the shortcut so you won't get screwed.
I also played against a guy this afternoon that only picked Rainbow Road the entire time. I hit 'em up with 2 Baby Parks and powerslid his ass off the course.