It was always going to either be "they become friends" or "Deadpool shoots Pinkie", and I'm glad they went with the former. It also went in a direction I didn't expect regarding that.
Two Pinkie Pie things I'm a bit surprised they didn't bring up:
* Pinkie's sister, Maud, is very strong and fast, disregarding toon force. This doesn't necessarily imply anything about Pinkie, but in the Sombra alternate timeline from "The Cutie Re-Mark", she's shown to be as strong as Maud, with both of them punching through a large boulder.
* In the newest Equestria Girls film, the human alternate universe version of Pinkie gained the ability to turn small objects into explosives.
Both don't apply to the main universe version of Pinkie, but for a battle, it wouldn't have been out of the question to bring them up.
Deadpool's sections were good, but that's to be expected. I was impressed by how well Pinkie's new lines were integrated into old scenes, though it was obvious to me when a different VA was used.