Hasbro's sales reps have to take some responsibility though as to what products get sold and how much of each are sold and where. A store chain doesn't know what will sell and what won't, nor would they necessarily know to buy a product related to a tv show that is not out yet, let alone if that product exists.

They would be relying entirely on the information provided by the toy company's sales reps. That includes the estimated popularity of each toy, so if a Hasbro sales rep for example says that OP and BB are the main characters in a movie or tv show so they will therefore be the most popular amongst the kiddies who are our main target audience, then of course the stores will rely on that "intelligence" and buy 10 times more of that particular product than the rest of the line.

This is my understanding of the process of course, I don't actually have any experience in the mechanics of how these transactions take place but am happy for people to correct me if I'm wrong.