The water parks are tricky to navigate with a WC. One issue is that the slides end up at various places, not always obvious from looking at the structure. My son can walk, but has bad balance, bad depth perception, weak muscles, takes stairs very slow etc (Downs and autism). Uses a Convaid chair at the parks. For a time we would get him to the top for one slide ride (2 man tube or family raft ride), then my husband would take him over to Lazy river for the rest of the morning, or wave pool, while I did slides with siblings. Then I would take him back to room after lunch, other kids would stay with DH. We had multiple issues trying to use the lift at BB, then get a WC brought over at the top to wait in the line up top, then leave that WC with a confused CM. Get to the bottom and try and figure out where we left the Convaid chair. Got to be a struggle.
DS is now an adult, but of course still loves water slides. We stick with the hotel slides now, BW clown slide is really good, it is big, and one of us can wait near the bottom and watch him come down. (Beach Club is not as good for him, with that long walk across the public sidewalk, plus it is long and straight and sort of slow, vs the twisty one at BW.) The hotel slide allows him to ride several times, vs the one ride down at the water park.
This is just our experience, it will be a different choice for other folks.