Good Afternoon,
We stayed at WL last May with our then 9 month old. The crib we had was a pack n play type. It is perfectly okay. We also stayed at Dixie and the Polynesian last year and we had wooden cribs. I think it depends what is available when you check in. I'm sure that as the wooden ones are retired they are replacing them with the fold up kind because they store and transport so much easier.
Tell them to enjoy the trip with the baby. If possible they should take their own stroller because then if the baby is fussy you can walk them around the hotel and then just let them sleep in the stroller.