The "main 5" in the 80's and 90's was Kermit, Piggy, Fozzie, Gonzo and Animal. Every postcard, merchandise, toy line, etc only featured those guys.
But somewhere in the late 90's I noticed Rizzo started getting merchandise, and got added to the main core. Then later the main core changed to Kermit, Piggy, Fozzie, Gonzo and Pepe. Pepe was almost overshadowing Kermit by the 2000's with saturation. Even I, a massive Pepe fan, was feeling it was a bit much.
The original "core" of the Muppets was Kermit, Rowlf, Harry the Hipster, Yorick and Sam. Actually Kermit and Rowlf were pretty much the only main standout muppets for about 15 years.
By the late 70's the core became of course Kermit, Piggy, Fozzie, Gonzo, Rowlf and Scooter. So it's quite nice to see Scooter back.
I do see Walter as more a Bean character. A regular character, but perhaps not a focal point. Then again Johnny Fiami and Sal became main characters after awhile
Overall, with the movie...as much as Im disappointed Rizzo and Pepe aren't in it save for a couple cameos...Im even sadder Carl is relegated to a background character. Since 2008 Big Mean Carl was being positioned as one of the main regular muppets with a number of scene stealing roles *still a huge Carl fan*