In California state court, the document most practitioners think of as a "motion to dismiss" is actually a demurrer, governed by Code of Civil Procedure §§ 430.10–430.41. A demurrer challenges the legal sufficiency of the complaint itself — it asks the court to assume every well-pleaded fact is true and decide whether, even so, the plaintiff has stated a viable cause of action. If the complaint also contains improper allegations (irrelevant matter, conclusory statements, requests for relief the plaintiff cannot recover), you'll often pair the demurrer with a motion to strike under § 435.
Timing matters. A demurrer must be filed and served within 30 days of service of the complaint, and § 430.41 now requires the demurring party to meet and confer in good faith at least five days before the deadline. Skipping the meet-and-confer declaration is one of the most common reasons demurrers get continued or overruled on procedural grounds.
A well-built California demurrer has six structural pieces: (1) a caption block matching the operative complaint; (2) the notice of demurrer and hearing date reserved through the court's online reservation system; (3) the demurrer itself, identifying each cause of action attacked and the statutory ground; (4) a memorandum of points and authorities, with controlling California authority — not federal Rule 12(b)(6) case law; (5) a § 430.41 meet-and-confer declaration; and (6) a proof of service.
Two drafting traps to avoid: pulling facts from outside the four corners of the complaint (judicial notice is narrow), and arguing the merits of disputed facts (save that for summary judgment). The demurrer lives or dies on whether the pleading, taken on its face, states a claim — keep your brief disciplined to that question and you'll write a motion the court can actually grant.