first of all , i would like to say that i am sorry for not including kisame in my poll (i had a brain fart moment)
in my opinion , the only who would be able to pose a treat to tobi would be itachi(as said for manga)
nagato is no doubt powerful and almost above itachi , but we dont have enough proof to support this theory(i may be wrong).
and for sasuke posing a threat i have just one word lol !!!!