My guesses for understudies on Sesame Street
-Grover (Paul McGinnis, as he performed him back at the '03 SW Gala)
-Cookie Monster (Tyler Bunch, if not then Paul McGinnis)
-Baby Bear (Paul McGinnis, as his speaking voice is similar to David's)
-Grundgetta (Stephanie D'Abruzzo)
-Telly (Tyler Bunch)
-Rosita (Haley Jenkins, if you watch Haley in Victor Yerrid's Pitch Perfect 2 Cup Song video, she has moments where it seems she is definitely capable of performing Rosita's voice, granted it wouldn't be as authentic as Carmen)
-Abby (Stephanie D'Abruzzo)
-Count von County (Tyler Bunch)
-Bert (likely an unknown)
-Snuffy (likely an unknown, Noel is only 7 years younger than Marty, so it wouldn't make sense for him)
-Murray (Ryan Dillon)
Any comments?