Decorate dress. Use tip 3, a cut disposable decorating bag and light teal icing to pipe straps on shoulders. Pat smooth with finger dipped in cornstarch.
For hem, use tip 2A, a cut disposable decorating bag with coupler and medium teal icing to pipe a line of five balls at base of dress. Use 9 in. angled spatula to pull icing upward from center of each ball. Continue piping lines of balls and pulling to complete a row around the cake. Repeat to pipe a second row of balls overlapping tails of the first row and staggering position.
For side ruffles, move doll arms up and out of the way. Use tip 102, cut disposable decorating bag with coupler and medium teal icing to pipe a bottom ruffle 3 in. deep, from center of front to center of back. Repeat with four more rows of ruffles inside the first and slightly overlapping to complete one side. Repeat for opposite side.
Use tip 2 and medium teal icing to pipe dot neckline and waistline. Use tip 3 and medium teal icing to pipe dots on edge of hem and on front between side ruffles.