Do you actually make the gifs or do you just get them from another website? :u
because by the looks of it, you're only getting them from one website that provides people with the actual animations from the pokemon games.
honestly i dont find it fair to sell images you find off another site unless you somehow customise them yourself, and im p sure it's also a form of theft, but you can always check with staff members.
if somehow i'm misunderstanding, i deeply apologize!