Regular sized strollers may be rolled onto the Monorails, as well as the Ferry's (TTC <--> MK) and the Cruisers. (WL/FW & Epcot Resorts). Oversized strollers, including some double strollers MAY have to be folded for the Monorail and/or Cruisers.
Due to size restrictions, strollers must be folded for the smaller Launch boats. Strollers also must be folded prior to boarding any bus, for safety reasons, as well as legal restrictions.