I'm not sure exactly what your situation is. It you were cited, then you should have gotten some paperwork to appear in court. If you didn't get any paperwork, then you should not have a court date. In any event, your best bet is to seek legal counsel. I'm sure that there is a lot more to the story, including what you and your friend to the police after the wreck. If the case is very weak as you indicate no breath test you may be better off fighting it. But the standard is very low for underage consumption. If you admitted to consuming ANY alcohol, you may have given the officer enough to be a problem. In such situations, it is hard not to say too much to the cops. Go with a lawyer before you go to court.
Yes plead not guilty and get an attorney because you don't want this on your record. Criminal history will haunt you for a very long time so fight it and don't drink alcohol