Mario Party DS Cheats - Nintendo DS

Unlockables
Rocket Rascals - Beat Boss Bash
Music and Voice Room - Finish story mode once
Expert CPU Difficulty Level - Complete Story Mode
Triangle Twister Puzzle Mode - Complete Story Mode

Unlock Badges
Bob-omb Rival badge - Earn 15,000 Mario Party points.
Boo Rival badge - Earn 7,000 Mario Party points.
Cheep Cheep Rival badge - Earn 5,000 Mario Party points.
Daisy Master badge - Complete Story Mode with Daisy.
Goomba Rival badge - Earn 1,000 Mario Party points.
Luigi Master badge - Complete Story Mode with Luigi.
Mario Master badge - Complete Story Mode with Mario.
Mario Party DS Begginer badge - No need to unlock. You start with it.
Monty Mole Rival badge - Earn 13,000 Mario Party points.
Peach Master badge - Complete Story Mode with Peach.
Scuttlebug Rival badge - Earn 3,000 Mario Party points.
Shy Guy Rival badge - Earn 9,000 Mario Party points.
Toad Master badge - Complete Story Mode with Toad.
Toadette Friend badge - Earn 19,000 Mario Party points.
Waluigi Master badge - Complete Story Mode with Waluigi.
Wario Master badge - Complete Story Mode with Wario.
Whomp Rival badge - Earn 11,000 Mario Party points.
Wiggler Friend badge - Earn 17,000 Mario Party points.
Yoshi Master badge - Complete Story Mode with Yoshi.

Unlock Boss Trophies
You can see them in the gallery section:

Beaten Dry Bones - Beat Dry Bones 5 times
Beaten Hammer Bro - Beat Hammer Bro 5 times
Beaten Kamek - Beat Kamek 5 Times
Beaten Piranha Plant - Beat Piranha Plant 4 times
Bomb Seed - Beat Piranha Plant 3 times
Bowser's MegaMorph Belt - Beat Bowser once
Delicious Durian - Beat Dry Bones twice
Dry Bones's Bone - Beat Dry Bones 4 times
Electromagnetic Generator - Beat Bowser twice
Enchanted Bookcase - Beat Kamek twice
Hammer Bro's Hammer - Beat Hammer Bro 4 times
Jagged Leaf - Beat Piranha Plant once
Kamek's Blue Dictionary - Beat Kamek 4 times
Kamek's Brown Book - Beat Kamek 3 times
Magic Switch - Beat Dry Bones 3 times
Toadette's Chair - Beat Hammer Bro once
Toadette's Piano - Beat Hammer Bro twice
Toadette's Timpano - Beat Hammer Bro 3 times
Winner's Ballon - Beat Piranha Plant twice
Winner's Pen - Beat Kamek once
Yummy Lychee - Beat Dry Bones once