I had problems with the fortune wheel, until a friend of mine (Who has no life, spends every waking moment on video games, and then tells us the tricks) told us how to beat it.
Basically, you put the cursor over the bottom right hand corner of the wheel, (corners on wheels, WTF, I know, but trust me) and wait till the pokemon you want is on the bottom left hand corner (again with teh corners). Drop the marker then. by the time the marker has landed on the wheel, it should land on the pokemon you want. It worked for me most every time, and got the pokemon I wanted.