There are cups at aid stations. That said, unless you are really fast, as in sub 2:45 fast, it is best to bring a bottle with you so you can have a drink between aid stations. The gap between Barr Camp and A-Frame is about 45 minutes for somebody on a 3:30 pace. Continuing on that pace, you will then have another 40 minutes until you get to the cirque.
The wide mouth hand bottles are the easiest to refill at an aid station and we can usually do it in only a few seconds. The folks who show up with the recycled water bottles that have an opening measured in milimeters are a royal pain and take 10x longer.