Wii Sports [Wii]

Never lose skill points
When you have lost a match in tennis, baseball, or boxing, immediately press Home before the game displays "You lose". Then exit to the Wii menu. If timed correctly, when you reenter the game your skill level in that sport should not have decreased.

Quicker fitness tests
You have the option for taking a fitness test which includes stamina, power and speed. Because of the default settings, you can only take the test once a day and must wait till the next day before retaking it. Use the following trick to take the test dozens of times a day. Go into the Wii system settings and select the calendar option. From here, just move the date up by one day. This will trick the game into thinking that a day has passed and you can retake the test.

Bowling: Gutter ball
Knock down all the pins except for the 10 or the 7 pin. You can then put the red dotted line about three-fourths of the way and still be on the lane, and not in the gutter. Do not release the ball when it arches up and drops on to the lane, because the ball will go into the gutter.

Bowling: Other player's pins cannot be knocked down
Move your Mii so he or she is in the gutter. Then, press A and aim the ball at the lane next to yours. Your ball will go in the wrong lane. Howvever, you cannot knock their pins over.

Tennis: Enter the crowd
When your opponent hits a ball on either side that will be an out, flick your wrist. Your Mii will jump for it and end up where the fans are.