Itachi's complete Susano form can't be broken through, Sasuke's non-complete one could though (Demonstrated by the Raikage, as well as fracturing the bones, but even at A's strength he still couldn't break it, unless his leg drop would have done it but we weren't able to see that outcome), Although Mei seemed to do pretty good against it with her KG's, but then again Sasuke was out of chakra so doubt anything can truly break Susano's defense, just my opinion though.he'll have an opening while defending himself from everything else. Now, dont tell me he's defense can defend everything. Question can't it be pireced?