Nintendo has been at it for the last 30 years, here are landmark lawsuites lists, from my memory everything relevant has been listed.

https://emulation.gametechwiki.com/index.php/Legal_status_and_history_of_emulation#Nintendo

And there are a few points why they are so active, first and foremost the IP law in Japan, which says (paraphrased) that IP that is not defended is fair game for everyone; then there is the technological fact that emulation of their systems is pretty easy performancewise nowadays in comparison to the naughts; and then there is the thing that if the few titles that are exclusives to nintendos system can easily played on other platforms (where they don't see a dime), they will not be able to sell their hardware and therefore no games that are available on other platforms. Also, they have always stepped up their game when a new hardware generation comes out - can't have people emulating the old platform when there's new stuff to buy, ya see?

I await the day when someone at nintendo starts using his calculator and recognizes that selling their back catalogue games at 7,99 per game on pc and 10 bucks on all the other platforms would ensure a steady flow of income for much needed innovation; the switch is nice, but i can't see where the switch 2 is a product that shows enough difference to the switch1 for massive sales.