Unlockables:-

Condition:

Special Kit 3 (Mini-DK) Beat Nine of the Mini-Games
Special Kit 2 (Mini-Peach) Beat Six of the Minigames
Special Kit 1 (Mini-Toad) Beat Three of the Minigames

Unlock construction kits for creating custom levels.

Condition:

Tropical Island construction kit Beat Donkey Kong at Tropical Island
Toadstool Castle construction kit Beat Donkey Kong at Toadstool Castle
Spooky Attic construction kit Beat Donkey Kong at Spooky Attic
Pipe Works construction kit Beat Donkey Kong at Pipe Works
Mushroom Mayhem construction kit Beat Donkey Kong at Mushroom Mayhem
Magnet Mania construction kit Beat Donkey Kong at Magnet Mania
Lava Dome construction kit Beat Donkey Kong at Lava Dome
Jungle Hijinks construction kit Beat Donkey Kong at Jungle Hijinks

Unlockable Pictures for Mario vs. Donkey Kong 2: March of the Minis:

Unlockable: Condition:

Picture 1&2 Beat DK in floor 1
Picture 3&4 Beat DK in floor 2
Picture 5&6 Beat DK in floor 3
Picture 7&8 Beat DK in floor 4
Picture 9&10 Beat DK in floor 5
Picture 11&12 Beat DK in floor 6
Picture 13&14 Beat DK in floor 7
Picture 15&16 Beat DK in floor 8
Picture 17 Beat DK in Roof
Picture 18 Beat Hidden Boss 1(B1) in basement

Unlockable Movies for Mario vs. Donkey Kong 2: March of the Minis:

Condition:

Musical Beat Hidden Boss 2(B2) in basement.
Ending Beat the final boss in the Roof.
Introduction Start a file in Main Game.
Unlock title screen characters

You can unlock different minis to stroll across the title screen by getting various medals in the game (purely cosmetic). It also changes the music at the title screen to a retro theme.

Condition:

Donkey Kong Minis Get Golds on all 80 levels
Princess Minis Get Silvers on all 80 levels
Toad Minis Get Bronzes on all 80 levels