Complete the following tasks to unlock the indicated character. There are multiple ways to unlock characters.

Unlock Birdo:
At Yoshi Park defeat Bowser Jr.

Unlock Daisy:
Complete Peach's Stadium.

Unlock Baby Mario:
Unlock Baby Luigi then at the field where you battle Bowser Jr.'s team save Baby Mario.

Unlock Baby Luigi:
At Mario's Stadium pull the levers to connect the bridge.

Unlock Baby Daisy:
At Peach Garden use Wario’s magnet to pull Daisy’s baby rattle from the fountain. Then have Yoshi go through the manhole cover on the left side of the garden to give the rattle to a crying Baby Daisy.

Unlock Baby DK:
At DK Jungle use Yoshi's power to free Baby DK from the palm tree that he's stuck in. Alternately, defeat DK's team.

Unlock Baby Peach:
At Peach Garden use Princess Peach's heart power on the grass Toad statue.

Unlock Blooper:
At the dock in Mario Stadium have Princess Peach use her heart power on the bubbles in the water. Alternately, complete ALL tutorials in Practice mode.

Unlock Blue Noki:
At Mario's Stadium complete Blue Noki's task.

Unlock Green Noki:
Unlock and have Blue Noki on your team. Then at the beach at Mario's Stadium talk to Green Noki.

Unlock Red Noki:
Unlock and have Blue Noki and Green Noki on your team. Then on the giant clam at Mario's Stadium talk to Red Noki.

Unlock Paratroopa:
At Wario City defeat the minion guarding the lighthouse.

Unlock Red Paratroopa:
At Yoshi Park find the paintbrush and then use it to paint the giant billboard at Wario City.

Unlock Funky Kong:
At the DK Jungle save Funky Kong from the Hammer Brother.

Unlock King K. Rool:
At the DK Jungle defeat ALL four Kritters. Then go to the waterfall and defeat him.

Unlock Kritter:
At DK Jungle defeat King K. Rool.

Unlock Red Shy Guy:
At Yoshi's Ballpark shoot the Piranha Plants.

Unlock Red Yoshi:
Find the brush that Red Yoshi lost and then find him at Yoshi's Stadium.

Unlock Tiny Kong:
At DK Jungle defeat Bowser Jr.

Unlock Wiggler:
At Yoshi Park reset the roller coaster that Wiggler is riding. Alternately, win a game at Toy Field

Unlock Waluigi:
In Wario City find Waluigi on top of a skyscraper.

Unlock Yellow Pianta:
At Mario Stadium find Yellow Pinata in a barrel.

Unlock Yellow Yoshi:
At Yoshi Park use Yoshi to get Yellow Yoshi out of a tree.

Unlock Goomba:
At Wario City help Goomba trace his shop.

Unlock Green Koopa:
At Wario City free Green Koopa from the poster.

Unlock Toad:
Start Peach's Stadium.

Unlock Green Toad:
At Peach's Stadium complete Toadette's puzzle successfully and then search the bush.

Unlock Toadette:
At Peach's Stadium talk to Toadette.

Unlock Blue Pianta:
Get the key and save Blue Pianta from the shop at Mario's Stadium.

Unlock Blue Shy Guy:
At Yoshi's Ballpark shoot the Piranha Plants.

Unlock Boo:
At Wario City have DK and Wario solve the block puzzle.

Unlock King Boo:
At Wario City talk to the Tiny Boos in a chest.

Unlock Monty Mole:
At Mario Stadium use Peach on the Monty outline on the beach.

Unock Paragoomba:
In Wario City use Yoshi's ground pound on one of the palm trees.

Whenever you beat a minigame a new setting with increased difficulty will become unlocked. This will continue happening in each minigame until the maximum difficulty setting has been reached.

When you complete the indicated task the corresponding hidden minigame will become an available option.

Unlock Blooper Baserun (Day) Minigame:
Unlock Daisy’s Cruiser

Unlock Castle Pinball (Night) Minigame:
Unlock Bowser’s Castle

Unlock Graffiti Runner (Day) Minigame:
Unlock Bowser Jr.’s Castle

Unlock Wall Ball (Night) Minigame:
Defeat Bowser Jr. In Challenge mode

Unlock Bomb-omb Derby (Night) Minigame:
Defeat Bowser Jr. In Challenge mode

Unlock Ghost K (Night) Minigame:
Unlock Luigi’s Mansion

When you have found the Secret Shop you will be able to buy the following 3 items.

Star Candy:
Find and purchase in the Secret Shop

Star Candy (x2):
First purchase a lone Star Candy

Super Star:
First purchase three sets of Star Candy (x2)

To find the following Error items unlock Wario and use his treasure opening ability at the indicated location in Challenge mode.

Fire Ball:
Wario City

Mini Boos:
Mario Stadium

POW Ball:
Peach's Ice Garden

The last movie in this crazy game becomes unlocked when you defeat Bowser twice.

This feature is unlocked when you beat Star level on every minigame. In Minigame madness you play 5 random minigames and win points agganst your friends or computers. You get 10 points for coming first, 8 points for coming 2nd, 6 points for coming 3rd and 3 points for coming 4th. Minigame Madness cannot be played in Challenge mode.

If you want a change of scenery then complete the indicated task in Challenge mode to unlock the corresponding hidden field.

Unlock Bowser's Castle:
Defeat Bowser in Challenge mode.

Unlock Bowser Jr. Playroom:
Defeat Bowser Jr. At this stadium in Challenge mode.

Unlock Daisy Cruiser:
At Peach Ice Garden buy the Cruiser pass at the shop.

Unlock Luigi's Mansion:
At Mario Stadium buy Luigi's flashlight at the shop.

Collect the following badges by completing their corresponding task.

Unlock Buddy Badge:
Get every character on your team.

Unlock Star Badge:
Make ALL playable characters star characters.

Unlock Stadium Badge:
Open ALL the playable ballparks.

Unlock Error Item Badge:
Unlock ALL the Error Items

To be able to play during the night at the different stadiums you must first beat Bowser Jr.'s Playroom in Challenge mode. Night mode is not available for Bowser's Stadium or Luigi's Mansion.