Hi Kayla,
Awww! I remember those potty-training days with my oldest son.
The beauty about visiting the Disneyland Resort Parks when the little ones are learning to
go on their own, is that there are
Baby Care Centers inside each Park.
These Baby Care Centers offer a quiet place to feed, nurse and change your child. They also have small toilets (perfect for toddlers and preschoolers) so that they can potty comfortably!
The Baby Care Center in Disneyland is located along Main Street, U.S.A., right across the Little Red Wagon hand-dipped corn dogs Cart.
The Baby Care Center inside the Disney California Adventure Park is located toward the back of the Paradise Pier area (across from the Ghirardelli Soda Fountain).
Now, in terms of taking your own toilet seat riser for your little one, I think that as long as it fits inside your diaper bag, you shouldn't encounter a problem getting it through the gates.
I hope this helps!
Thanks for visiting the Disney Parks Moms Panel!
Please visit again if you have additional travel questions pertaining to the
Disneyland Resort.
-Anabel M.