It seems like their claim to fame is the ability to play retro games in-browser. They also charge a membership fee for an ad-free experience. My guess is that this isn't about the availability of warez, but the monetization of in-browser gameplay. Nintendo states "unfair competition" as a basis for the lawsuit.
It's about the warez availability too. It's for each and every single of these reasons: (i got this from the lawsuit, sorry if there's something i copied wrong)
copying, distributing, selling, performing, displaying, playing, or otherwise using any unauthorized copy of a Nintendo copyrighted work, or any derivative thereof, including those works identified in Exhibit A; b. using, inducing, or enabling others to use any unauthorized reproduction or copy of Nintendo’s copyrighted works, including the works identified in Exhibit A; c. constructing, operating, selling, or otherwise providing any product, device, website, or service that contributes to or induces the reproduction, distribution, performance, display, or other use of Nintendo’s copyrighted works, including the works identified in Exhibit A; d. using, or inducing or enabling others to use, any reproduction, counterfeit, copy, or colorable imitation of Nintendo’s trademarks, including those trademarks identified in Exhibit B, in any manner in connection with the manufacture, printing, distribution, advertising, offering for sale or sale of any goods or services, including the use of Nintendo’s trademarks in connection with a website; e. using, or inducing or enabling others to use, Nintendo’s trademarks, including those identified in Exhibit B, or any reproduction, counterfeit, copy, or colorable imitation of said marks in any manner likely to cause others falsely to believe that Defendants’ products or services are connected with Nintendo or legitimate Nintendo products or services bearing Nintendo’s trademarks when they are not, including the use of Nintendo’s trademarks in connection with a website; f. destroying, transferring, altering, moving, returning, concealing, or in any manner secreting any and all unauthorized copies of Nintendo’s copyrighted works and any and all documents and records, including without limitation computer tapes, computer disks, business records, e-mails, social media accounts, social media posts, supplier names and addresses, books of accounts, receipts, and other documentation relating or referring in any way to the distribution, provision, use, or otherwise trafficking in unauthorized copies of Nintendo’s copyrighted works; and g. unfairly competing with Nintendo.
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