A friend has requested a Curious George cake with whipped topping. Ok. So I suggested I could do him in icing, but the I thought about it and I don't know how that would work. With buttercream, I could use piping gel and smooth on the different colors pretty easily. With whipped topping, won't the colors fade, etc??? How should I put George on there? Also, would a buttercream transfer just sink down into the whipped topping? I appreciate any suggestions.

I would do the top in buttercream, add the transfer and then ice the rest in the whipped topping. Another thought is to make George on a candy melt plaque and place that on top of the whipped topping.
HTH