When a pleading is filed it must contain a factual statement that support a legally recognized claim. For example, to modify a timesharing and parenting agreement or order in a family law case, you must prove that a substantial change in circumstances has occurred since the order was entered.
If the pleading fails to allege a legally recognized claim, the typical procedure is to file a motion to dismiss the pleading for failure to state a cause of action. If you fail to file such a motion in the first instant, your ability to seek dismissal of the claim may be waived.
However, there is another procedural device that can be used to contest the legal sufficiency of a pleading even if you fail to file a motion to dismiss the pleading and instead file an answer. Under Rule 1.140(h)(2) of the Florida Rules of Civil Procedure, a party can file a motion for judgment on the pleadings that tests the legal sufficiency of the pleading which can be done before or at a trial.