I personally prefer paying for all the stuff I consume in order to support the creators, but Nintendo has made it pretty much impossible for us to play our old titles. Typically the rules behind ROM files is that as long as you own or have own a physical or digital version of the game than you are technically okay to get a ROM file of that game. I will share with you the ones that I have gotten ROM files from while I was working on this article/video of How to Use ps4 Controller on Dolphin Emulator on Mac.
This is the part that I cannot go too much in to details due to the nature of the legal complexities of the handling of ROM files, but know that it is quite simple to find a good site and download them.
