So here is what I found and just copy and pasted + what I figured out...
Bowling
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
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.
Tennis
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.
Super Serve
When you serve the ball just hit it in it's highest point and it will give full throttle.
The big Tennis lie
There is no difference between fore- and backhand. It just takes you time and confuses you to switch the side you smash the ball. Simply stay on the forehand side even if the ball is coming on your backhand. Much more enjoyable ;-)
Golf
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.
Boxing
Silver Boxing Gloves
After you've beaten the Grand Champion, Matt, in a boxing match you'll be able to wear silver boxing gloves. To do so, hold (1) when the screen becomes black before a boxing match.
Unlockables
Special Bowling Ball
Get to pro level to unlock a bowling ball with diamond designs on it.
By the way - am I the only one righthanded not gettin' the right effet? It's so hard to do - even the straight ones always have left effet :'(
Bowling
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
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.
Tennis
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.
Super Serve
When you serve the ball just hit it in it's highest point and it will give full throttle.
The big Tennis lie
There is no difference between fore- and backhand. It just takes you time and confuses you to switch the side you smash the ball. Simply stay on the forehand side even if the ball is coming on your backhand. Much more enjoyable ;-)
Golf
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.
Boxing
Silver Boxing Gloves
After you've beaten the Grand Champion, Matt, in a boxing match you'll be able to wear silver boxing gloves. To do so, hold (1) when the screen becomes black before a boxing match.
Unlockables
Special Bowling Ball
Get to pro level to unlock a bowling ball with diamond designs on it.
By the way - am I the only one righthanded not gettin' the right effet? It's so hard to do - even the straight ones always have left effet :'(