Assemble cake. Prepare buttercream icing following recipe directions. Tint portions leaf green/lemon yellow combination (for green) and bright rose. Reserve remaining white.
Use spatula and rose icing to fill bottom cake half cavity to level. Use two separate disposable bags, each fitted with tip 12, to pipe alternating rows of rose and white icing to fill top cake half cavity. Stack cakes on foil-wrapped cake circle or cake plate. Use spatula and green icing to spatula ice cake fluffy.
Use cake dividing chart to divide cake into eighths. Insert one small and one large cake pop eye at each mark, 1/2 in. from edge. Position candy-coated chocolate in front for nose. Insert candy tentacles into cake sides.