Spread frosting on the tops of the cupcakes and set aside.
With a serrated knife, cut the graham crackers widthwise into seven pieces: four 3/4-inch pieces, two 1-1/4-inch pieces, and one 2-inch piece. Then, spread a thin layer of frosting on top of each graham cracker. Pour the sugars into individual bowls. To coat, press the 2-inch piece into the blue sugar and the 1-1/4-inch pieces into the green sugar. Press each of the 3/4-inch pieces into a different-color sugar.
Arrange the frosted cupcakes in a vertical line. Place the blue graham cracker horizontally on the top cupcake to make the head. Line up three of the multicolored crackers on the middle cupcake and press one on the very top of the bottom cupcake, to make the body. Place the green crackers on the bottom cupcake to make legs.
Thread four pieces of cereal on two of the lollipops and stick one on each side of the middle cupcake for the arms. Stick the remaining lollipop in above the head with two pieces of cereal below for the neck.
Place the pink flat sprinkles and mini candy-coated chocolates on the head to make eyes. Pipe the mouth and other designs with the chocolate frosting. Decorate with candy-coated chocolates.