Your definition is correct for "legal non-conforming".The "legal" part of "non-conforming" is dropped when it doesn't apply so most commonly people call these units "non-conforming", "finished", "in-law suite/unit", or "bonus unit".Non-conforming: Any property that doesn't meet current zoning requirements.Legal non-conforming: A non-conforming property that was lawfully established under previous zoning regulations and is allowed to continue its use.Based on his posts @Mario Morales is referring to a non-conforming unit.

But, now laws are much stronger, identity much more difficult to hide.  

I'd try to understand landlord laws in each market - i.e. figure out which markets are more landlord friendly.

He may get stuck with rent control laws that prevent him from catching up later. 

Just getting my feet wet out there over the last three years and its good to see the post and the additional feedback from some really savvy and experienced investors.Built about 10 cabins last year as I talked my ex brother in law into moving out there two years ago and getting our gc license. 

Some STR hosts have switched to MTR though with the laws so maybe you just have a supply problem there.

I was recently looking into wholesaling in PA around the Wilkes-Barre area and was wondering about the overall laws and regulations.

Local laws are often changing too which can affect your business.

My main question though is, does California law require that I use the specific C.A.R.

There's a bunch of houses out there with "in law" units that make ADU conversions simple and affordable.