Right before the Elements struck, the Nightmare unleashed a spell out of desperation. A substitution spell. Otherwise known as the correct use of Kawarimi.
Anon is pulled into Equestria by a long-lost artifact belonging to Discord. Without the ability to speak or write clearly after being transported, Anon is placed in Fluttershy's care.
Friendship is a give-and-take relationship. Fortunately for you, Pinkie doesn't ask for much, and she has plenty to give. Maybe it's time to start giving back.