Pokemon did have "active" toys for the 7th movie being promoted by Subway. Remember those? Plastic thingies with pokemon stickers on them?
The point is, McDonald's and Burger King not only reach out to the most kids, but also provides a much stronger financial backing as well as more aggressive advertisement than Subway or whatever-the-place-you-named-that-we-don't-have-around-here.
So blame fast food for fatty food, but it's what gets the word out quicker.
('Sides, can't you substitute the fries for apple sauce or something, and get a diet soda or iced tea or milk? A plain hamburger really isn't that bad, though personally I stay away from the fried chicken tenders)