When you activate Pumpkin Minnie's skill a number of 'candies' will fall from the top of the screen. If you click on them they will clear the surrounding Tsums. If the hit the bottom without you tapping them then they will clear the Tsums at the around the point they hit the bottom. Tapping them while they are falling will normally clear more Tsums; however, they fall very fast and quickly so it can be very hard to tap them all. Her skill isn't very powerful especially since it is capped at skill level 3.