Posted By: wraggster
Via gamefaqs
Codes
Change bowling ball color
As The screen is fading to black for bowling, hold down the control pad until it fades to bowling for these colors:
Code Effect
Control Pad Up Blue Ball
Control Pad Right Gold Ball
Control Pad Down Green Ball
Control Pad Left Red Ball
Change the tennis court
To change the tennis court to the blue practice court, press and hold (2) at the warning screen that shows after selecting characters.
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.
Unlockables
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.
Special Bowling Ball
Get to pro level to unlock a bowling ball with diamond designs on it.
Easter Eggs
Scare Crowd in Bowling
To scare the crowd while bowling, start the regular motion for bowling and let go on the backswing. The ball will fly backwards and the crowd will scream and jump.
Secrets
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