the question now is...why obito. cuz im still really not feeling the because he was super weak he needed a super weak body excuse.
*gasp* edo tensei. tobirama could be controlling obito from afar in secret
but why obito >_>. as kabuto proved with this war, there were dozens of better options.
wait wait wait
tobirama is sealed up by the god of death after that orochimaru vs hiruzen incident.