Mario vs. Donkey Kong 2: March of the Minis Tips

Mini Game: Shy Guy Smash
Collect all of the Cards (One in each level to spell out MINIMARIO) to unlock the Mini Game for that world.
The Minigame is always Shy Guy Smash, but of varying degrees of difficulty and different Pipe layouts.

Beating the Minigames will send you on the way to get the Special Construction Kits.

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