weaker than sasuke?we know nothing about tobirama from the manga, except that he was the best water user in history and that he had some sort of s/t jutsu (probably weaker than minato's and definitely weaker than sasuke's). and he did not complete edo tensei so i don't think that he could use it.
so probably the uchiha bros take this
/facepalm .....you must not read the manga...you would know Tobirama had his own version of edo tensei, and he used it many times, seeing that Madara, muu knew about it.......did not complete edo tensei so i don't think that he could use it.