Anilrgowda

Unlockable: Special Bowling Ball You must achieve pro level on the bowling game.
Submitted by faredell
Unlockable: Tennis court
At the warning screen after selecting characters, hold down 2.
Submitted by weezy

Hint - Barrier Strike
For the 'Power Throws' training game in bowling, turn either left or right until there are four red bars pointing in the direction of your choice across the bowling line. This may not always work, especially with the big numbers of pins but this will almost always give you a strike. Feel free to experiment with different numbers of red bars across the bowling line since three and four almost always work for me.
Submitted by David Khan

Hint - 91 Strike
In the "Power Throws" training game for bowling, you might notice 2 red buttons at the end of the alley - 1 left and 1 right. When you get to the final bowl for 91 pins, you can bowl the ball along the top of the barrier on either side and hit this button.

Move your Mii all the way to the left or right, and turn the aim 2 or 3 clicks towards the barrier. Let go of the ball at the highest point possible, with just a bit of spin to keep the ball on the barrier.

If successful, you will hear a click, the screen will shake and all the pins will fall down.
Submitted by peterv1000

Mii Parade
You can add more Miis in Parade and audiences. Use Wii Sports to do it:

1. Make about 10 Mii's.

2. Transfer those Mii's to your Wiimote.

3. Delete the Mii's that are transfered to the Wiimote out of the plaza.

4. Start up Wii Sports.

5 When given the option of which Mii to use during gameplay choose the option to get the Mii from the Wii Remote.

6. After viewing the Mii's on the Wiimote back out by using the B button.

7. Exit out of Wii Sports and back onto the Wii Menu.

Now check the Mii parade and all 10 of the Miis that were on the Wiimote are in the parade. Now if you dont want the Miis on the Wiimote just delete them off. These Miis will now show up in all Wii Sports games that have an audience.
Submitted by Meganutts

Bowling Ball Color Change
You can select your bowling ball color before you bowl by using the directional pad. When you reach the screen warning, 'Make sure nothing is around you', hit the A button and hold the D-pad (until the alley UI appears) to choose your color:

UP = blue
LEFT = red
DOWN = green
RIGHT = yellow