I'm going to unlock all characters, their star versions, stadiums, minigames, error items, and badges in this walkthrough. I'll be going for the characters and items first, then will do the minigames last.
In this part, I utterly defeat Bowser Jr. and his cronies. Then, the true big bad appears. I go to the Secret Shop and buy a Star Candy.
Badges/Stages/Items/Characters Obtained:
Bowser Jr.'s Playroom
Luigi's Mansion
Star Candy
Stages:
Mario Stadium [x]
Peach Ice Garden [x]
Yoshi Park [x]
DK Jungle [x]
Wario City [x]
Bowser Jr.'s Playroom [x]
Bowser Castle
Luigi's Mansion [x]
Daisy Cruiser [x]
Toy Field [x]
Minigames:
Bob-Omb Derby
Wall Ball
Piranha Panic [x]
Barrel Basher
Gem Catch
Graffiti Runner
Bowser Pinball
Ghost K
Blooper Baserun
Toy Field
Minigame Madness
Items:
Nice Bat [x]
Power Bat [x]
Dr. K [x]
Lucky Glove [x]
Dash Spikes [x]
Buddy Badge [x]
Error Booster [x]
Charge Bat [x]
Star Candy [x]
x2 Star Candy
Superstar
Error Items:
Shell [x]
Banana [x]
Bob-Omb [x]
Fireball [x]
Mini Boo [x]
POW Ball [x]
Special Items:
Luigi's Flashlight [x]
Cruiser Pass [x]
Special Shop Pass [x]
Toy Field Pass [x]
Paintbrush [x]
Sea Hut Key [x]
Daisy Statue [x]
Toad Statue [x]
Stone Tablet Piece 1 [x]
Stone Tablet Piece 2 [x]
Stone Tablet Piece 3 [x]
Baby Daisy's Rattle [x]
Badges:
Star Badge
Stadium Badge
Error Item Badge [x]
Buddy Badge
Play Badge
Characters (x means unlocked, S means star version unlocked):
Mario [x]
Luigi [x]
Peach [x]
Daisy [x]
Yoshi (Green) [x]
-Red [x]
-Blue [x]
-Yellow [x]
-Light Blue [x]
-Pink [x]
Birdo [x]
Baby Mario [x]
Baby Luigi [x]
Baby Peach [x]
Baby Daisy [x]
Toad (Red) [x]
-Blue [x]
-Green [x]
-Purple [x]
-Yellow [x]
Toadette [x]
Toadsworth [x]
Pianta (Blue) [x]
-Red [x]
-Yellow [x]
Noki (Blue) [x]
-Green [x]
-Red [x]
Shy Guy (Red) [x]
-Blue [x]
-Yellow [x]
-Green [x]
-Gray [x]
Wario [x]
Waluigi [x]
Petey Piranha [x]
Wiggler [x]
Monty Mole [x]
Blooper [x]
Donkey Kong [x]
Diddy Kong [x]
Dixie Kong [x]
Funky Kong [x]
Tiny Kong [x]
Baby DK [x]
King K. Rool [x]
Kritter (Green) [x]
-Red [x]
-Blue [x]
-Brown [x]
Goomba [x]
Paragoomba [x]
Boo [x]
King Boo [x]
Koopa (Green) [x]
-Red [x]
Paratroopa (Red) [x]
-Green [x]
Bowser
Bowser Jr.
Hammer Bro
-Fire Bro
-Boomerang Bro
Dry Bones (Gray)
-Green
-Dark
-Blue
Magikoopa
-Red
-Green
-Yellow
Teams:
Mario Fireballs [x]
Peach Monarchs [x]
Yoshi Eggs [x]
DK Wilds [x]
Wario Muscles [x]
Bowser Monsters
Characters Obtained: 58/71
Star Characters Obtained: 0/71
Error Items Obtained: 6/6 all Error Items found
Badges Obtained: 1/5