You can try taking the screenshots of your iMessages conversations. I agree, without the date & time stamps and speaker information your text conversations wouldn't help much in a legal matter. Remember you might also need to testify that you received these messages on that particular date and they are accurate depiction of what you recived, and for this you might need an affidavit.
A few months back, I needed to print my iPhone text messages/imessages to use them as evidence in a legal suit and a third party app recommended in this guide did the job for me. You can use this app to export your text messages and iMessages to your computer as PDF and then easily print them off. Text messages will be saved with all the vital information such as date stamps, time stamps and speaker information such as contact name and phone number. Similar to other tools this is also a shareware program. You might also find this Apple Stack Exchange discussion about printing iPhone text messages for court useful.