All of the pictures of the costumes. Top left: marvelgirl2010 / Via Flickr: 57918907@N05 
Top middle: Several Gerhing Juniors going as Beanie Babies (no specified photographer)
Top right: Costumet Team / Via costumet.com Middle left: Walmart Coustumes / Via walmart.com
Middle: Dancing Girls Emoji Costume / Via no specific photographer.
Middle right: Alvin and the Chipmunk Costume / Via brit.co
Bottom left: The Beatles / Via ebay.com
Bottom middle:
Bottom right: Nerd Costume / Via halloweencostumes.com