Stamps - Successfully complete the indicated task to unlock the corresponding stamp:

1-Stage Master: Finish all 1-Stage races in first place.
100-Pointer (Return Challenge): Get a score of 100 points or more.
200-point Dive: Get a score of 200 points or more.
200-Pointer (Return Challenge): Get a score of 200 points or more.
3-Stage Master: Finish all 3-Stage races in first place.
5,000-pointer (Power Cruising): Get a cumulative score of 5,000 points or more overall.
50-Pointer (Return Challenge): Get a score of 50 points or more.
6-Stage Master: Finish all 6-Stage race in first place.
A Cut Above: Defeat the Speed Slice champion.
A For Effort: Score 10 points with each of your 10 throws to get this stamp.
A Secret To Everybody: Hit all the secret targets in every level.
Archery Bull Stampede: Hit the center of the target and get 10 points with all three arrows in one stage.
Back From the Brink: Successfully return a ball that hits the edge of the table.
Bag Of Tricks: Land seven or more different kinds of jumps on a single run.
Balloon Animal: During practice, pop all 9 balloons in ten throws or less.
Balloonatic: Pop every white balloon at all times of day.
Beginner License: Get to 200 yards in the Beginner level.
Bonus Plumber: Score every Bonus Ball worth 2 points in a 3-Point Contest.
Buzzer Beater: Make a last-second shot with a "buzzer beater", a basket scored just before the buzzer signals the end of the game.
Camera Shy: Do not catch anybody on your dive, and the photographer will come out from behind the camera for a special shot.
Century Shot: Shoot 100 arrows into the target.
Cut the Red Tape: Cut the red tape in all levels.
Double Time: Slice the alarm clock when the two digits on the display are the same, such as 8.8, 7.7, or 6.6.
Ducks In A Row: During Canoe pratice, return all of the ducklings to the mother, then complete the next canoe speed race.
Ducky Come Home Stamp: In Canoeing, catch all ducklings and take them to their mother in practice.
English Major: Score 170 points or more without hitting a single barrier.
Epic Rally: Keep up a rally (hitting the ball back and forth without stopping) for 30 hits.
Expert License: Get to 400 yards in the Expert level.
First of Many: Finish a race in first place for the first time.
Follow That Plane: Follow Miguel's guide plane around the island for at least three minutes.
For The Birds: Take a photo with a bird in it.
Friends In High Places: Catch at least 29 Mii characters during your dive, then join them for the final formation and have a picture taken.
Frisbee Dog Good Dog: Throw the Frisbee right into the center of the target area to make the dog jump up and grab it out of the air.
Frisbee Golf Under Par: Finish 3-, 9-, or an 18-hole course under par.
Gobble Gobble: Bowl three strikes in a row to get a turkey.
Golden Arm: Score 100 points with every throw and pop every balloon.
Head First: Knock down the headpin in every game.
High Five: Catch and link up with four other Mii characters, and make sure everyone's face is visible when the camera snaps.
High Roller: Get a score of 200 points or more.
Hole In One: Throw the Frisbee into the target area in just one throw.
Hoop Hero: Take down the champions in a Pick-Up game.
Hot Streak: Score 5 balls in a row in 3-Point Contest.
In Your Face: Hit your opponent's face with the ball.
Intermediate License: Get to 300 yards in the Intermediate level.
Island Hopper: Visit any "!" point on Wedge Island.
Last Gasp: Finish a race while you are out of breath.
Last Mii Standing: Defeat the champion in a duel.
Leisure Cruiser: Find all the time balloons in one run in Single Player Free Cruising mode, then complete the Slalom Course afterwards.
Lights Out: Drain five 3-point baskets in one game.
Lucky Skip: Get this stamp when a Frisbee bound for water hazard skips across the surface of the water and lands safely on the other side.
Master Carver: Score 1,000 points or more on the Expert level without hitting any obstacles.
Met Your Match: Draw three rounds in a row to get to the final battle ring, then draw again for a completely even match in Single Player mode.
Not The Face Stamp: In Table Tennis, hit your opponent in the face with the ball.
Off the Wall: Hit the gutter guard once, and then get a strike.
On A Roll: To pull off a "roll-in," throw your Frisbee from outside the green, hit the ground, and roll it into the goal.
One For All: Knock down at least one pin in every frame.
One-Hit Wonder: Push your opponent out of the ring with only one strike in Single Player mode.
Perfect 10: Clear Stage 10 without taking a single hit and losing a heart.
Perfect Game: Bowl 12 strikes in a row.
Perfect Target: Hit the center of the target area and score 100 points with all ten of your throws.
Perfectly Matched: Draw with your opponent in Single Player mode.
Pin Dropper: Score a strike or a spare on every frame.
Pin Dropper (100 Pin Bowling): Score a strike or a spare on every frame.
Pin Dropper (Spin Controll): Score a strike or a spare on every frame.
Pop Frenzy: Pop 150 balloons during one flight.
Power Cruiser: Score 170 points or more on all courses.
Power Jumper: Go through all the bonus rings in the final course.
Psychic Slice: Cut an object correctly before it even hits the ground in Single Player mode.
Pure Shooter: Sink all 25 balls in the basket with at least 15 seconds left on the clock.
Quick Draw: Finish throwing all 25 basketballs as fast as possible.
Recycler: Knock the can off the table with a ball 30 times in one game.
Rim Rattler: Score three slam dunks in one basketball Pick-Up game.
Ringmaster: Go through every single bonus ring on one course.
Save Face: Get a score of 100 points or more without the ball ever hitting the server's face.
Secret Strike: Roll the bowling ball all the way across on the gutter guard.
Sharpshooter: Score 10 points with every arrow in each of the 4 rounds.
Showdown Not a Scratch: Clear any stage without taking a hit and losing a heart.
Slicing Machine: Correctly slice at least one of each of the 18 types of objects in Single Player mode.
Smooth Landing: Land 10 jumps in a row.
Speed Slice Slice and Dice: Win the contest without missing a single object by slicing the wrong way or failing to slice within the time limit.
Split Spare: Get a spare after getting a split on your first throw.
Split Spare (100 Pin Bowling): Get a spare after getting a split on your first throw.
Split Spare (Spin Control): Get a spare after getting a split on your first throw.
Straight And Narrow: Play an 18-hole round of Frisbee Golf without throwing any discs out of bounds or into a water hazard.
Straight To The Point: Push your opponent out of the ring with a lunge in Single Player mode.
Super Strike: Knock all 100 pins down with one huge strike.
Sure Shot: Hit the target with all 3 arrows in each of the 4 stages.
Sword Fighter: Defeat all of your foes to clear the first 10 stages.
Swordmaster: Fight through the final Showdown stage.
Swordplay Duel Cliff-Hanger: Reach the final battle ring by both opponents still being locked in a draw after three rounds. It does not matter if you win or lose.
Table Titan: Defeat the table tennis champion in a match.
The Long Way Home: Land 50 jumps and wakeboard all the way around Wuhu Island in Free Cruising mode.
Triple Dip: Score a basket from beyond the 3-point line in a Pick-Up game.
Under Par: Finish a round of golf under par.
Untouchable: Fight through the final Showdown stage without taking a single hit and losing a heart.
Wakeboarding Huge Air: Score 100 points on a single jump.
Wuhu Tour Guide: Collect all the "!" points in the daytime, evening, and night.

Pro class - Get a "1,000" rating in any sport. You will see a silver seal next to your name when you play that sport and have the following bonuses unlocked:

Air Sports: Unknown
Archery: Unknown
Basketball: Unknown
Bowling: Star ball
Canoeing: Unknown
Cycling: Basket bike
Frisbee: Three extra hard holes
Golf: Three extra hard holes
Power Cruising: Unknown
Swordplay: Second samurai armor
Table Tennis: Unknown
Wakeboarding: Two bonus courses

Superstar class - Get a "2,000" rating in any sport.

Never lose skill points - Pause the game when you are about to lose a match. Either restart or quit before the game displays the score. If done correctly, you will not lose skill points.

Replay Skydiving introduction in Air Sports - Use the following code to replay the skydiving demo that was featured when the game was first started. At the character selection screen, highlight the pointer over the "OK" option. Hold 2 and press A. Release 2 at the next screen, featuring your Mii getting ready to jump. If done correctly, your score and level will not appear.

No guide circle in Archery - Achieve Pro class in Archery. Then while an Archery game loads, hold 2.

Play at night in Basketball - While confirming your character at the selection screen, hold 2 and press A. Release 2 at the warning message screen.

Super Mario 64 reference in Basketball - During a 3-point contest, you can sometimes hear the "Wa-ha!" sound said by Mario in Super Mario 64 after a triple jump.

Change ball color in Bowling - For a golden ball, hold Right and press A while confirming your character at the selection screen. Release Right at the warning message screen.

For a green ball, hold Down and press A while confirming your character at the selection screen. Release Down at the warning message screen.

For a pink ball, hold Left + A while confirming your character at the selection screen. Release Left at the warning message screen.

Secret Strike in 100-pin game in Bowling - You must throw the ball on top of the right or left rail. To do this, move to the rail, but set your direction and position options before getting too close to the rail. The dotted line must be almost parallel to the rail, but slightly turned towards the rail. If you are too close to set the angle, move away then move back in after making your adjustment. If done correctly, after a perfect throw, the ball will roll on top of the rail and hit the red button at the end. You will hear a click followed by the sound of an explosion if that happens. All 100 pins will then fall down. After completing the match, you will also get the Secret Strike stamp.

Scare crowd in Bowling - When the Wii-mote is all the way behind you when throwing the ball, release B. If done correctly, the ball will be thrown backwards and the Miis will jump.

Animal Crossing reference in Bowling - When you zoom in, the sound is the same as when the menu is displayed in Animal Crossing.

Bonus races in Cycling - Successfully complete the indicated task to unlock the corresponding race:

1-Stage Race: Over Talon Rock: Successfully complete three 1-Stage races.
1-Stage Race: Up The Volcano: Successfully complete five 1-Stage races.
1-Stage Race: Into Maka Wahu: Successfully complete seven 1-Stage races.
3-Stage Race A: Successfully complete three 1-Stage races.
3-Stage Race B: Successfully complete three 3-Stage races.
6-Stage Race: Get approximately 650 event points.

Basket bike in Cycling - Achieve Pro class in Cycling. Then while selecting your Mii, hold 1. There are two versions, depending on the gender of your Mii.

Control view in Cycling - Use the D-pad at the map to control the camera angle and look around the island. Note: You can also change camera views while riding.

Mario Kart series references in Cycling - At the start of a race during the countdown, the sounds are the same as during the pre-race countdowns in the Mario Kart series.

When you fall off a cliff, the sound is the same as when you fall off a cliff in Mario Kart 64. - Alternate controls in Dogfight

You can use the following controls on a Nunchuk any time during flight:

Use the Joystick to change camera angles.
Press Z to fire bullets.
Press C to cut the engine.

Three Holes - Special course in Frisbee Golf - Successfully complete all courses with a total score that is under par (-1 or better) for each hole.

Remove meters in Frisbee Golf - While confirming your course at the selection screen, hold 2 and press A. Release 2 at the warning message screen. The only meter visible will be the one that sets the direction when you are on the green.

Three Holes - Special course in Golf - Successfully complete all courses with a total score that is under par (-1 or better) for each hole.

Remove meters in Golf - While confirming your course at the selection screen, hold 2 and press A. Release 2 at the warning message screen. The only meter visible will be the one that sets the direction when you are on the green.

Remove "i" symbols and balloons in Island Flyover
At the "Select time of day" screen, highlight the "Daytime", "Evening", or "Night" option, then hold 2 and press A. Release 2 at the "Warning" screen.

Island Flyover unlockables - Get the indicated number of points by collecting "i" symbols in Free Flight mode to unlock the corresponding bonus:

Balloons appear over Wuhu Island: 10 points
Evening mode: 20 points
Double Popper: 30 points
Night mode: 40 points
Night fireworks lighting: 50 points
Two-seater plane: 60 points
New Whale Shark design featuring your Mii: 70 points
Vacation house: 80 points

Finding Miguel in Island Flyover - When you follow Miguel's plane, you will find some "i" symbols. Use the following trick to locate Miguel's plane. Press 1 to shoot a flare. A flare will also appear and can be heard from Miguel's plane soon afterwards. Keep firing flares until you find Miguel, then follow him.

Alternate controls in Island Flyover - You can use the following controls on a Nunchuk any time during flight:

Use the Joystick to change camera angles.
Press Z to fire bullets.
Press C to cut the engine.

Super Mario Bros. reference in Island Flyover - Go to the hillside cabins at night. You can hear someone playing Super Mario Bros.

Bonus courses in Power Cruising - Successfully complete the indicated task to unlock the corresponding course. Note: The courses will be unlocked separately in Shalom and Versus mode.

Cavern: Play Power Cruising ten times.
Marina: Play Power Cruising five times.
Shoals: Play Power Cruising fifteen times.

See whale in Power Cruising - Play at night in Free Roam mode. Look for a whale jumping. Go to where it landed to see it swimming underwater.

Play at sunset in Swordplay - While confirming your character at the selection screen, hold 2 and press A. Release 2 at the warning message screen.

Purple sword in Swordplay - Defeat Matt, the Pro class champion, then hold 1 while a Swordplay game loads.

Punch opponent in Swordplay - Go for a swing, then quickly block at the last moment. You will punch your opponent in the face with a little knock back.

Fight the champion in Swordplay - Duel - Score 1,500 points to fight Matt, the Pro class champion, in a special sunset match.

Samurai armor in Swordplay - Duel - Score 1,000 points to unlock the Samurai armor Level 2.

Upgraded Samurai armor in Swordplay - Duel - Defeat Matt, the Pro class champion, to upgrade your Samurai armor to Level 3. Note: You must have 1,500 skill points to face him.

Punch opponent in Swordplay - Duel - End with tie at sudden death. A screen with both you and the CPU opponent standing next to each other will appear. You can repeatedly punch the CPU character in the face.

Reverse mode in Swordplay - Showdown - Successfully complete the Volcano round to unlock the Reverse rounds. You can play all ten original rounds backwards.

Shoe or slipper paddle in Table Tennis - While a Table Tennis game loads, hold 1.

11 point game in Table Tennis - While a Table Tennis game loads, hold 2.

Bonus levels in Wakeboarding - Get between 400 to 500 points in the overall event score to unlock the Intermediate level. Get between 800 to 900 points in the overall event score to unlock the Expert level.