Janette = troll, pikachu, Juliet gnome
Dianne = monkey from Aladdin, Marge, Miss Piggy
Amy = tiger
Kev = minion, (cyberman)
Pash = Shrek, Bergen
Aljaz = Baloo
Nat = penguin
Brendan = Tramp (dog)
Many have had the short straw, it just appears that Janette and Dianne embrace it somewhat.
I think it was last year I said, I expected Janette to turn up as Sonic the hedgehog at some point (Where evil grows is a decent song, mind) or Rosita from Sing! (Gio missed a trick there).