you can't use recorded conversations between two people recorded in CA without all parties consent. I ti a criminal offense. Go to legal aid but you need an attorney to present your best case.
This is just my opinion and not a comprehensive answer. You assume the risk because this answer may not apply to your situation depending on the facts.
This does appear to be retaliation, and would be suitable for a jury trial.
Unfortunately, asking for a jury trial will significantly delay going to trial, so it may be hard to predict when you will actually commence trial.
The plaintiff's case in chief is going to be pretty simple if it is based upon failure to pay rent. You will probably need to subpoena witnesses to testify as to the condition of the rental dwelling. You need the other tenant's live testimony to bolster your case.
The recordings will not be admissible evidence, but the photographs will if you lay a proper foundation. Your testimony will be sufficient to authenticate these photographs as depicting whatever you intend for them to show.
Frank W. Chen has been licensed to practice law in California since 1988. The information presented here is general in nature and is not intended, nor should be construed, as legal advice. This posting does not create any attorney-client relationship with the author. For specific advice about your particular situation, consult your own attorney.