Yeah.... they would have gotten complaints about not have Cait Sith there. But like, i've done alot of research, and im very confident that im correct in saying....

Red was not in the movie very much because his fur was VERY expensive to animate. As would have Cait Sith's giant moogle. All they could afford to do was Red, so they just said "Hey, lets put Cait Sith on Red!"