Suppose there is a missing link between the Canon Universe of MLP:FIM and A Non-Canon Universe.
So here is my Theory
If Twilight were to Fail her entrance exam she would probably leave Canterlot in shame, Which means Spike would have never met Twilight, Which also means Twilight cannot run a Library. She would possibly run to Ponyville were she would go to the School, and Meet Applejack, and Rarity. Applejack would probably become freinds with Twilight first, Then she would do something to help out Rarity, which would make them freinds, Twilight would then meet Pinkie Pie then they would also become freinds. Eventually They would meet Fluttershy, and they Would help her out with her Animals, Or try at least, and they would become freinds. After preforming the Soinc Rainboom Rainbow Dash would have looked for Fluttershy, Considering that she wasn't in Cloudsdale, And found her on Earth, Rainbow would try and Convince Fluttershy to come back up because the Earth is gross and dirty and Full of germs. Fluttershy becomes a neat freak and doesn't let anypony into her house. Twilight discovers that a Pony named Rainbow Dash told her that. Twilight tries to convince Rainbow to Talk to her, But she says that "Pegasus ponies belong in the sky, Not on the ground!". Twilight and Applejack come up with a plan to get Rainbow to apoligize and, Of course, It would work. Rainbow Dash would become freinds with the 5 and then the Original Plot would take place once again. Twilight and the 5 would encounter Nightmare Moon. Twilight and the 5 make a run to Canterlot where they find a Book on Nightmare Moon. They find the Elements of Harmony and Defeat Nightmare Moon. Celestia would arrive and She that Twilight had proven her worth, Twilight's Cutie Mark would appear at that moment, And Celestia would take her as her Apprentice.
No matter what happens, The Mane 6 would meet, and they would defeat Nightmare Moon
So what do you guys think?