Re: WHO'S HERE? SHARON stopped by to see the pool and congratulate Stephen on his efforts to improve the campus. Because she did eventually join the crew in Hawaii in the 80s, she has a swimsuit! - that is definitely better for beach sunbathing than Cannonball contests, but she'll have thrown a light weight shirt on over it for the general party and will get in the pool for a bit. She'd be chatty (for her anyway) with anyone that's around.
HUGH is there because he was helping Vax host. He found a basic pair of swim shorts in the costume room, and is wearing those (they're deeply boring, but oh well), and his own soft t-shirt, until he gets in the water and gets wet and then that's going. He'll hover around the food table to make certain things stay stocked, and is available for all the chatting with anyone and everyone.
BEN is Baymax, so he is not swimming. He will come, and watch. If asked, he's there in case of medical emergency. He guesses. He will fidget as much as a Baymax can fidget because he doesn't really know why he's there or what to do with himself without eating, drinking, or swimming. He might leave early.