Nintendo can use anything you create and submit on their platforms for any purpose, without paying you or asking for further permission, potentially indefinitely.
Nintendo's Terms of Use significantly shape users' legal rights by requiring binding arbitration for disputes and waiving the right to participate in class action lawsuits. The terms also grant Nintendo a broad, perpetual, royalty-free license to use any content users submit through their platforms. You can opt out of the arbitration agreement by sending written notice to Nintendo of America within 30 days of first accepting the terms.