Justin Success Brooks, 41, is said to have sold thousands of illegitimate copies of DS, DSi and Wii between 2009 and 2011, making £600,000 along the way, the Croydon Guardian reports.
His activities came to light following a joint investigation between Nintendo and UK Interactive Entertainment, who purchased games from dubious outlets to trace the products back to their supplier.
Brooks, from Purley, has been charged with seven counts of fraud, including "two counts of fraudulent trading, two counts of supplying an article to use in fraud, two counts of unauthorised possession of goods bearing a trademark and one count of unauthorised use of a trademark".
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Nintendo is well known for its vigilance against piracy. The company had a court ban the sale of writable Nintendo DS cartridges in 2010, and uses firmware updates to tackle the issues on 3DS.
Brooks, who could now face a jail sentence, is on bail until sentencing is passed on November 9.