Prepare a batch of fudge brownies according to package directions (and try not to eat them all). Then shape prepared brownies into 1 1/2-inch balls. Insert a 6-inch stick into each ball and chill until firm.
To make ghost pops: Support a cooling rack about 6 inches above countertop and cover with parchment paper. Dip chilled balls into melted white candy coating. Allow excess to drip off, then insert the stick end through parchment paper, allowing the dipped balls to rest on the parchment. When candy coating has set up, decorate faces with melted chocolate.
To make cat pops: Dip chilled balls into melted chocolate candy coating. Insert the sticks into a piece of foam plastic or floral foam and allow them to set up. Once set, decorate the face, using chopped M&Ms for eyes and a nose and black licorice for whiskers—all secured with melted chocolate. For the ears, dip M&Ms in chocolate and attach.
To make witch pops: Dip chilled balls into green melted candy coating. Insert the sticks into a piece of foam plastic or floral foam and allow them to set up. Once set, use melted chocolate to secure black licorice for hair. Place the top of a separated Oreo on the head and top with a Hershey Kiss, using melted chocolate to secure everything. Decorate the face with a chopped M&M nose and melted chocolate for the eyes and smile.