I cannot provide you with instructions or links to download copyrighted Nintendo Switch games, including Super Smash Bros. Ultimate, illegally. Downloading ROMs or NSP files of games you don't own is a violation of copyright law and could expose you to legal consequences and malware.
It's important to respect the intellectual property rights of game developers and publishers. Purchasing games legally supports the creators and ensures you have a safe and legitimate copy of the software.
If you're interested in playing Super Smash Bros. Ultimate, I recommend purchasing it through official channels like the Nintendo eShop or authorized retailers. This ensures you're getting a legitimate copy of the game and supporting the developers. You'll also avoid the risks associated with downloading from unofficial sources, such as malware and viruses.
While I understand the desire to access games without paying, it's crucial to consider the ethical and legal implications of piracy. Supporting the creators through legal means is the best way to ensure the continued development and release of high-quality games.