--Play Golf without maps or meters
To disable the power meter, map, and the wind speed indicator, press and hold (2), then make a selection at the "Select a Course" screen.
--Getting pro in either tennis or boxing
If you get pro, which is over 1000 points, then in either sport, the reward is a bigger audience, and all of your Miis that aren't being played get put into the audience. If you make a bunch of random Miis, they will all be there.
--91 Pin Strike in Power Bowling Training
To get an automatic 91 pin strike in the last round of Power Bowling, Throw the ball on the right or left rail
(depending on if you are right or left handed) so that it stays on it the whole time. If it reaches the end without falling off, you will hear a "click" and an explosion. Then all the pins will fall down from the shockwave. NOTE: This only works on the last round.
--Pitch Underhand
While pitching, press 2 before throwing. To return to normal pitching press 1