Even though they didn’t meet each other in Deadpool, both Weasel and Dopinder were key supporting players in the movie.
That said, Weasel’s only willing to go so far for his best friend, as he sat out the final battle against Ajax, Angel Dust and their minions because he just didn’t want to go.
As for Dopinder, he picked up the Merc with the Mouth twice in his cab, and when we last saw him, he’d just gotten into a car accident while his romantic rival Bantu was in the trunk.
Weasel already knew Wade Wilson pre-experimentation as the bartender at the mercenary bar, and he accidentally came up with the name that Wade would adopt to strike terror into the hearts of his enemies…or just confusion.