After trying to decorate my daughter's cake by hand icing a pegasus, I decided that one of her plastic pegasus toys (clean of course) would do the trick!
"I have had great success with dressing up the Costco sheet cakes: extremely low priced, and way too big for any party we've had. I've always thrown theme parties at home for my kids, changing the games to fit the theme."
"One year my son had a 'safari' party; I bought the Costco sheet cake which was decorated with a teddy bear driving a jeep, and placed little plastic animals all over the top. We had these animals around the house, I just washed them carefully. The kids LOVED it ("I want the piece with the giraffe!" "I want a lion!") and didn't even mind that they couldn't keep the animals, because my son wanted them all back! Last year I did something similar with two Star Wars characters placed atop a homemade Duncan Hines cake, much like a bride & groom; with a candy space ship, "Happy Birthday" and stars from the supermarket."
"I know they make sugar Batman logos you can place on top of the cake. Then all you need is 3 or four action figures..."