I know of a company that owns a few Casa 212's and utilize the services of one type-rated pilot (the "PIC") and one non-type-rated pilot (the "SIC") simultaneously on the flight deck. This is a normal situation in the U.S. as the copilot does not need a type rating in order to serve as the second-in-command (although I have heard a few crews have been nailed by the UK CAA by flying corporate jets this way in recent years, so it may change soon, however, it has not changed YET).
In summary, it is legal to fly a Casa 212 in skydiving ops if the Captain/PIC has a CPL with type C212 on ticket and Copilot/SIC has a CPL without a type rating. There are additional requirements (like SIC has to be familiar with the airplane flight manual, have 3 sole manipulator of flight controls landings, et cetera...). AFM says 2 pilots required, so 2 pilots is the minimum flight crew. Anybody who flies with a non-pilot on the right hand seat is, of course, operating contrary to the AFM.
You can substitute PPL for CPL above, as long as all the legal requirements of a non-commercial flight are satisfied (note: in my determination and other informative sources, hauling skydivers who paid for the ride and when the SIC is not getting paid is still a commercial flight, so a CPL would be necessary).
(hint: the name of the company is Carolina Sky Sports in North Carolina, USA, as I have tried to get a job there in the past. You will be maintaining and painting airplanes in the off season, $300-something per week income, if the company hasnt started charging for that right seat time yet, so be warned!).
gdpf