Pastel Unicorns are toys that Phoebe likes to play with. Pastel Unicorns also has a T.V. series.
The known characters are the following below.
Phoebe once mentioned "Pastel Unicorns: Princess Marshmallow's Day at the Mall". It is unknown if this is a movie, or simply another T.V. series.
Phoebe also mentioned in another book that Queen Galaxia is one of her favorite Pastel Unicorns.
Pastel Unicorns is very similar to My Little Pony, since they both have unicorns in them.
Princess Sunbeam could be similar to Princess Celesta from My Little Pony, since Phoebe was playing with a Princess Sunbeam doll and she was saying "Go Boysenberry Swirl, and open the gates of Glitter City!"
Boysenberry Swirl is similar to Twilight Sparkle from My Little Pony, because Phoebe mentioned on the show, she grew wings just like Twilight's!