Do not transplant showy pink lady's slippers from the wild. Laws exist prohibiting its removal --- even without these laws, the root system of this plant is difficult to successfully remove from its native soil.
Transplant your potted showy pink lady's slipper during its dormant season, which occurs from fall through winter. Gently remove the plant from its pot and shake all soil off the roots.
Prepare a potting mix consisting of a purchased acidic potting soil and combine about 1 cup of both leaf litter and pine needles for every 1-gallon pot you are using.
Spread a 1-inch layer of your potting mix into your pot and then set the showy pink lady's slipper into the pot. Fill the pot to within 1/2 to 3/4 inch of the top with additional potting mix and press down gently around the base of the plant with your fingers.
Water your showy pink lady's slipper until water runs from the pot's drainage hole. Keep it in an area with filtered natural light: avoid deep shade and full sun.