Following is a list from AllEarsNet:
http://allearsnet.com/pl/restrooms.htm
The following is a list of Companion or Family Rest Room locations where members of the opposite sex can enter the restroom together when assistance is needed.
All First Aid locations have companion-assisted restrooms.
Animal Kingdom
Discovery Island opposite Flame Tree Barbecue, just before DinoLand USA entrance on the right
Harambe Village in the Mombasa Marketplace
Chester and Hester's Dinosaur Treasures in Dinoland USA
Near Maharajah Jungle Trek on the left before the entrance
Inside Maharajah Jungle Trek to the right as you exit the Bat House
Conservation Station at Rafiki's Planet Watch
Disney-MGM Studios
Opposite Star Tours
Right side of Millionaire building on Mickey Avenue
Rock 'N' Roller Coaster
Opposite The Twilight Zone Tower of Terror
Fantasmic! amphitheater
Right side of Lights, Motors, Action!
Epcot
Spaceship Earth On Left as you face SE
Spaceship Earth on Right as you face SE near Gateway Gifts
Future World West opposite The Land
Future World East opposite Test Track
Refreshment Port (right side of World Showcase - before Canada)
Morocco on the right
Germany on the right
Norway opposite the Viking ship
Magic Kingdom
Lower level of Cinderella's Royal Table in the Castle
Pirates of the Caribbean
Near Splash Mountain
To the right of Space Mountain
Mickey's Toontown Fair
Transportation and Ticket Center East Gate
Polynesian Resort
Great Ceremonial House 2nd Floor opposite 'Ohana
Blizzard Beach Water Park
To the rear of the Locker area on the north side of Main Change.
Typhoon Lagoon Water Park
Near Guest Services
Downtown Disney
Marketplace
Once Upon a Toy Store - inside restroom area
Between Guest Relations and Once Upon a Toy Store - outside
AMC Theatres - No companion restrooms
Pleasure Island - No companion restrooms
West Side - No companion restrooms