Yuffie with a cold was somewhat amusing, just because it slowed her down a little and she'd let everyone take care of her for a bit.

Aerith with a cold was more complex, as things didn't get done and everyone else seemed far more worried about Aerith than she was about herself. Wizards and faeries were called in to try to help her, even when all she wanted was a bit of peace and quiet.

Leon with a cold was, well... Leon didn't get sick. Not that he'd admit to at least.

And Cid with a cold... A city-wide emergency.