Wii Play

Alternate paddle in Laser Hockey
Before the timer starts, press A + B to use a different circular paddle.

Platinum medals
Successfully complete the indicated task to get a platinum medal in the corresponding event:
Billiards: Earn at least 63 points
Charge: Get a score of 325 points
Find Mii: Reach the 100th stage
Fishing: Score over 2,500 points
Laser Hockey: Score at least 16 goals and win the match
Pose Mii: Earn over 1,000 points
Shooting Mange: Earn over 600 points
Table Tennis: Return the ball over 200 times without missing
Tanks: Successfully complete the first 20 levels to get the Gold medal, then play through the game again, which now has 100 levels

Screen saver
Allow the game to idle at the Game menu. Your Mii will fall asleep and new music will play. Your Mii will eventually wake up and the music will return to normal.
Double shots in Shooting Range
During a single player game in the Shooting Range, press a button on a second Wii-mote. You will now have two sets of crosshairs, and if you are quick enough, twice the shots.

Mii movements
At the main menu, select your Mii and it will do different things. If you select its right arm, it will give you a thumbs up. If you select its left arm, it will wave. If you select its head, it will shake it. If you select its torso, it will jump. If you select its right leg, it will lift it up along with its hands. If you select its left leg, it will act as if it is about to fall.