Popular costumes vary from year to year depending on movies, world-events, weather and so on.
However some trends seem to come back year after year, like pumpkin costumes for dogs and superhero dog costumes. Mail carrier costumes for puppies are always a hit, and hot dog Halloween costumes seem to never go out of style. Try a front-walking costume for added laughs :-) so many choices. There is always one available that you will really love.