The Mini Peaches are Peach toys sold by the Mario Toy Company. They appear in Mario vs. Donkey Kong 2: March of the Minis.
The success of the Mario Toy Company because of its earlier toys, the Mini Marios, was so good that it allowed them to expand to sell other Mini-toys, including Mini Peach, Mini Toad, and Mini Donkey Kong toys as well.
Mini Peachs can be playable in the Construction Zone but Special Kit 2 has to be unlocked first. There are also Fire Mini Peachs.