Here's what I've experienced. To/from resorts, the TL busses usually share the same route with DTD. To/from resorts, the BB busses usually share a bus with AK. I know there are exceptions, time of day, etc. To answer your question, as far as I know there are no park to water park direct busses. Primarily, because there is no parking fee for the water parks!! This prevents one from parking at a water park (to save $$$) and bussing to a theme park.