Update: The final two major characters have also now been cast! Paul Schneider and Nick Offerman have been cast in the final two major roles for the pilot, with Schneider playing a parks and recreation committee member alongside Amy Poehler's Leslie Knope and Offerman playing their supervisor.
In some ways, Pratt's character is the one who sets the whole show in motion: It's his accident in the big, empty pit in Pawnee, Indiana (you know, the one Poehler's cleaning up in this promo) that brings Ann to the parks committee meeting in the first place. The pilot script didn't have a ton of other details about him — other than that he's a struggling musician, which effectively means he's unemployed.
To hear about Schneider and Offerman's characters, just
Schneider (that's him on the right) plays Mark, one of my favorite characters from the pilot: He once had a one-night stand with Poehler's character, but let's just say Leslie has assigned a bit more significance to the event than Mark has. Meanwhile, Offerman (on the left) will play Ron, the head of the parks and recreation department who ultimately wields a lot of power over the rest of the characters.
With those roles cast, the pilot should be ready to go. I'll be curious to see how it turns out when it hits our screens April 9!