Really, any yogurt with live cultures, the bacteria that makes milk into yogurt, should do the same thing as any yogurt that's labeled as being good for your digestion. Activia just gave a certain one their own name. Every time I've seen yogurt on Disney property it's been Yoplait. It had live cultures the last time I looked, but that was a while ago. Perhaps reading some labels next time you're at the grocery store would give you an answer.
If you don't want to worry about keeping yogurt cold in your cooler or finding it on the ship, you could try Acidophilus capsules. You can get them almost anywhere that sells vitamins and food supplements. The kind that don't need refrigeration after opening the bottle are the easiest to deal with while travelling. I take them every day and they work well.
Have a great trip!