I've tried a lot of cases. Never have I had difficulty admitting statements by my opponent's client. The hearsay rule doesn't keep it out. Ever.
These statements will be admitted if the defendants said them and if they are relevant to the issues in the case. Depending on the applicable law, statements by a party are either not hearsay at all or are subject to a hearsay exception. If they bragged about raping a girl, it would also comes in as an admission against interest exception to the hearsay rule, regardless whether you are a party or not.
The only way to keep this out is if a judge rules that the prejudicial value outweighs the probative value. That rarely happens when a defendant has made statements implicating themselves in a crime. (The big exception to this statement is when the statement is made to the police and then the whole Miranda nonsense comes into effect. I don't see that being a factor here.)