Naya Rivera (as character Santana Lopez)
Sam sings Baby in the episode "Comeback".
Entitled "End Credits" (Made Famous by Glee Cast)
Laryngitis!
Idina Menzel or Shelby the Vocal Adrenaline's (competitive glee club) coach
No, everyone sings the same tune.
The whole glee club sings Push It in season 1 episode 2, Showmance.
The song Artie sings is Dancing With Myself
Sam sings Baby in the episode "Comeback".
Gwyneth Paltrow
Entitled "End Credits" (Made Famous by Glee Cast)
Jill Scott sings this classic. It has been also be redone by Glee.
Rachel Berry (Lea Michele) sings taking chances
Laryngitis!
Vocal Adrenaline
Kristin Chenoweth
Christina Perri is never on glee however rachel berry sings it in the prom episode
Idina Menzel or Shelby the Vocal Adrenaline's (competitive glee club) coach