US Court Laws. Can a defendant in civil court write a motion to a judge in court records, so the judge will respond to it? Or is it?

There is no such thing as writing a motion in court records. I have no idea what that even means.

Can a Defendant write a motion? Yes, if he or she isn't already represented by legal counsel. A Defendant cannot both be represented and represent himself/herself.

In general an ex-parte motion means the other party is not present. I don't understand the purpose of an ex-parte motion. What are you SPECIFICALLY asking about? An application for a restraining order? Something else?

When you go to law school, there are several courses on proper court room procedure. You will have to read and study some big books on the subject. Even after that, most court lawyers work with an experienced lawyer for a year or two. So basically, you're asking for hundreds of hours of knowledge to be summarized in a few dozen words.

You need to make sure that the motion follows the proper format for the court, otherwise the judge will not even look at it.

Also - if you have your own lawyer, the judge will not accept a motion from you.