I have always used black embroidery floss for fusible applique. Why do you recommend using several different colours?
It is considered by the designers of these patterns that the use of colors that match the applique pieces being sewn, provides a blending effect which enhances the marvelous features of the animals, injecting them with additional realism. The use of black embroidery floss only, is consistent with traditional naive country style applique, and can be employed with these patterns should you wish to.