In my experience as a California attorney, normally there is a hearing on the motion. (In relatively rare cases, the judge may decide without a hearing.) The paper you file would be called an opposition to motion to quash subpoena (or opposition to motion for order quashing subpoena), not a motion to dismiss. You can include supporting facts that support of your opposition. However, you probably need a memorandum of points and authorities outlining the legal support for the proposition that the information is discoverable. In California, information is discoverable if it is relevant to the subject matter of the action or is likely to lead to the discovery of admissible evidence. There may also be issues relating to privilege or other issues. It is hard to tell the merits of the subpoena without knowing more about the case and the subpoena.
This response is for information purpose only and does not constitute a legal advice. This response does not create an attorney-client relationship.
I practice in Connecticut, so my answer is based on that experience. There almost certainly would need to be a hearing on the motion. You would file an objection to the motion to quash and explain why the documents are necessary. If the basis for the motion to quash is that more time is needed, you could reach an agreement to provide the additional time, or limit some of the documents requested. But if it is based on a claim that the documents are not relevant, and not likely to lead to the discovery of relevant evidence, you will probably have to explain all that in your opposition papers.
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In Maryland, pro se parties are held to the shame standard as attorneys. Thus, by going it on your own, you're proceeding at your own peril. As my colleague said, you would never perform dentistry on yourself, so why would you attempt to practice law? Do you know how to get evidence introduced at trial? Just because you have a document doesn't matter. Do you know how to authenticate documents?
You could be harming yourself much more than you're helping yourself.