You don’t NEED a lawyer, but you do need to be prepared to find out how much procedural bullshit you don’t expect.
You can make oral motions on the record, but unless the prosecutor agrees, the judge is unlikely to grant them.
You can file a written motion, but then it must be properly served, with a proof of service attached, and enough time for the opposing party to respond.
You can try a case yourself as well, but you still have to follow the rules of evidence and procedure. The judge will explain the rules to you, but they can’t “help” you.
And just like i probably couldn’t walk into your place of employment and do your job as well as you can, it’s unlikely that you’re going to walk into a courtroom and out-lawyer a prosecutor.
I fully endorse taking a human approach and asking if a reduced charge is a possibility, with an agreed fine, etc., but “just plead not guilty and hope the cop doesn’t show up” seems to be a wide-spread misconception about how traffic court works.