This is actually the first time this artist ever drew ponies And here is the description from the artist.
 
“Requested by
 
She loves Phineas and Ferb as well as My Little Pony: Friendship is Magic and wanted some of the characters mixed together.
 
Phineas, Ferb, and Isabella, along with a few other friends, venture from the colorful place of Marzipan City and come across Ponyville where they meet the ponies.
 
The pink one is Pinkie Pie
 
The white one is Rarity
 
The blue one is Rainbow Dash
 
The tanned one is Applejack
 
The yellow one is Fluttershy
 
And the pretty violet one is Twilight Sparkle.
 
Yeah, I added a little Total Drama, a bit of Fetch! With Ruff Ruffman, some Codename: Kids Next Door, some Simpsons, and a nice bit of TUFF Puppy in there because I think it would be cute how they would interact with the ponies.
 
Yeah, Fetch thought that because Rainbow Dash is so cute he took on her offer to fly with her. Too bad he didn’t realize that she’s the toughest flying pony around!
 
And Tyler hangs out with Applejack. Seems Lindsey isn’t the only blonde who’s crazy about him!
 
You all remember my Christmas drawing featuring the first appearance of Moe and Maya’s baby daughter Marilyn? [link]
 
Remember how I mentioned that Moe chose Dudley to be her godmother over Marge and Helen Lovejoy? [link]
 
He loves her so much and Marilyn feels the same way. And what can be cuter than having your goddaughter ride a beautiful and lovely pony?
 
Seems Fluttershy is becoming even more shy around the cool dog agent. And quite fond of him.
 
How is Rocky like Rarity? She’s so gorgeous!  
No boy like Fanboy and Kick Buttowski can resist that pretty face!”