Plywood has many variations. From plywood with veneer to exterior grade plywood. The main issue is flatness of the board. Pywood with veneers veneer is usually pretty flat. Though exterior grades tend not to be.
I machine a lot of AC-Fir with and without plastic laminate. Parts fairy in size, smaller parts are cut leaving about 1/16" and then cut thru with a final pass. The machine we use is a Komo with a large vacuum pump. The operator at times will have to flip the sheet or press down the sheet for the best results. Overall the results are pretty good though at times there are issues with parts. At times we have full sheets that cannot be used because of the warp in the board.
Roller hold down would resolve many of the issue I have come across. Roller hold down is not a standard feature on machines. I have seen it as an option for machines.
At the show last year in Vegas there was a company that was putting roller hold down on all of the machines in their product line. The company is an American company called Phantom CNC. There is a lot of information on youtube about the machines they offer.