susano is not invincible, danzo managed to make a rather big gap in it's back with just a simple wind slice technique, so I'm quite sure that deidara's suicide explosion would be able to obliterate a susano no mater what level it's in (not sure about itachi's due to the yata mirror but then again, an explosion is a 360 degre field of attack, it attacks from behind aswel)
only thing I could see a susano user do in the face of deidara's suicide explosion is try to get susano off the ground and use it to try to ride the explosions shockwave, get pushed away, perhaps the user might survive that (if he manages a good landing)
only thing I could see a susano user do in the face of deidara's suicide explosion is try to get susano off the ground and use it to try to ride the explosions shockwave, get pushed away, perhaps the user might survive that (if he manages a good landing)