I am being sued by a credit card company. I have already filed an answer to the suit and went in today to file a motion to dismiss for failure to attach the original contract to the complaint. I was told by the clerk that I would have to have the plaintiff's atty agree and sign off on the motion. Is this true? I know there is no way they would agree to this. Please advise!

No, this doesn't make any sense to me.

Perhaps you misunderstood the clerk. A few possibilities come to mind:

You didn't properly prove that you sent a copy to opposing counsel and so the clerk wants you to provide a receipt signed by the opposing party.
You are filing the motion too early or too late or something and so you would need to get the opposing party's stipulation to waive that rule.
The clerk is wet behind the ears and doesn't have a clue.

Ok it may be that I'm filing too early. This is what happened - I received a flyer in the mail stating that I am being sued by Citibank from a bankruptcy firm that wants to represent me. I was never served with a summons. When I called the courthouse the clerk informed me that I needed to come down and file an answer so that's what I did. In the meantime I've been trying to negotiate with Citibanks Atty but they are not offering me a settlement that I can afford. So I went to file the motion to dismiss. I never asked for validation of the debt... Is this something that I have to file for? Or just send a letter to the atty? What other procedures should I follow? Please help!

... When I called the courthouse the clerk informed me that I needed to come down and file an answer so that's what I did. ...

Sorry, but you already gave away your best defense by voluntarily filing an answer. You will never know, but it's possible that they would never have served you with process.

I know.. I just realized that. I should have never listened to the clerk. Should I just wait now? Will they send me a court date? Or should I continue to try and negotiate with them outside of court?

I would attempt to negotiate right up until the Judge ruled. You never know unless you try -

(Most people would scream I KNOW; I REALIZED THAT. You did not - congrats. You've got your wits about you where this is concerned. If you negotiate with good intentions, sincerity, I think you've got a good shot at it.