Room 1-4 (Mario vs. Donkey Kong: Minis March Again!)
From the Super Mario Wiki
The course features two mini toys.
The minis start on the left side of the stage, behind a formation of Pink Blocks spaces with some Pink Blocks. In order to reach the Goal Door, located higher up on the right, the toys must be led there with Pink Blocks arranged like a staircase.
Mini Mario Card
The Mini Mario Card is found on a platform on the left, immediately above the minis. The player must first use several Pink Blocks to lead the toys to the right, then build a staircase of Pink Blocks from there to the card.