I love how well this and they matches up together further also in symbolism. Surprise was the "Dummy Out" prototype version of Pinkie Pie while Vanellope... (I'm going to leave this out due to the few who hasn't seen the movie yet). Sugar Rush world would be a great paradise (for the most part) for Surprise if the candy part of Pinkie is inside her as well!
Great work and I enjoyed the movie and Vanellope alot (and based on Pinkie I feel I would like Surprise as well).
The only way legally the two might showed up would require alot of red tape (or if Disney got the rights), the wasteland from Epic Mickey (a place where prototypes, dummy out characters from all media types, and forgotten in time characters reside), and Kingdom Hearts world/game/data jumping/traveling (just thinking if a fanfic happened to have these two how it might go)