With the exception of two or three really weird faces and three scenes filled by Pinkie Pie’s shenanigans, the movie looks great, colorful, beautiful and overall much better than the TV show (something that makes sense and has to make sense).
So I don’t think Adobe Flash would be necessary or extremely essential for this movie.
EDIT:
Same to be quite honest. I find myself humming the tunes of the other songs and if someone were to ask me to sing some of the songs of the film, I’d probably be able to except for that one.
Help fund the $15 daily operational cost of Derpibooru - support us financially!