Legal Question in Business Law in California

There is no such form. You need to talk to a lawyer in person.

Did you receive anything more than the summons form? A summons is supposed to be used along with a Complaint. The nature and substance of the Complaint would dictate what's needed as a responsive pleading. Among the things one needs to know is whether the Complaint is "verified" or "unverified" by the plaintiff.

Depending upon the nature of the Complaint itself, you may have several strategies available. If the Complaint is unverified, a General Denial will probably be sufficient to prevent your default from being taken, and get you on the Court's calendar. (I assume this is NOT a small-claims case, although at under $5,000 it probably could be.)

Was there anything in the package you were served with setting a date, time and courtroom for a first hearing, probably a Case Management Conference? That date would give you a clue at which the case will progress, assuming you get an answer on file before the HOA requests the Court to enter your default.

Don't expect the Court clerks to give you legal advice beyond, perhaps, their basic procedural policies. Telling you which form to use is not a clerk duty. Indeed, probably 90%+ of lawsuits filed in Superior Court don't use forms for either the Complain nor the Answer, although use of a form for the Summons is quite general practice.

My advice would be to show all the documents that were served on you to a lawyer or paralegal and ask whether a filled-in form such as the PLD-050 or PLD-C-010 would suffice or whether, because the Complaint is verified or for other reasons, a written-to-order response (Answer) would be more appropriate. It'll depend upon what's in the Complaint that supposedly was served with the Summons.

You have thirty days from the date service is complete to file a responsive pleading with the court. That means an answer, or a motion to strike, or a demurrer, or a motion to quash. Which one of those you file depends on what is plead in the complaint, the way it was served, and other facts. Have you tried speaking to an attorney for some coaching or a brief consultation?