My favourite course is the stamina course.
I find it easy to get 500 points each time I do it (400 + 100 for winning it) as the games are relatively easy to use the stylus with, although I could be doing much better on the relay.
I use a team of
and an adamant
(Natures seem to influence pokeathlon stats), and its easy to do this half a dozen times to get an evolution stone that I need.