Here are his muppet show appearances:
Judy Collins: He appears in the sketch where kermit interviews him.
Edgar Bergan: He appears among the monsters in the number "Consider Yourself".
Steve martin: He leaves the audience at the beginning of the show.
the Koozebanian Phoob also appeared during the opening song in The Muppets Go To The Movies, and in the Jim Henson Hour special The Secrets of The Muppets, in the scene where a doozer comes to muppet central, one of the monitors shows both the blue and green phoob puppets dancing together. I do not kno if that image was from a previous production or not. In all of the appearances I listed, he was blue, but he turned green in his first sketch.