Hesusio: The article said the ban is 13 years old (so enacted around 2000 or so), so the N64 was perfectly legal up until the tail end of its lifespan.
True, true... Only : The iQue Player was released on 17 November 2003 with a few launch titles. Nintendo strategy to market games in China was to show how videogames can help improve children's mental and social development. At first, the only way to get games was to buy them via the iQue Depot, but in 2009, Nintendo released Fugue Online to download games at home. The latest game released was released in 2006.
(Source Nintendo )
And If I recall, the Zeebo (released around 2011 if I recall correctly) was meant for third-world markets among witch : China... So I really think that selling video game systems weren't as much illegal as monitored and strictly controlled.
Yet another article on wikipedia clearly states : On the other hand, video game consoles have been banned in the country since the early 2000s, in response to parental concern for youth productivity.
I really think that there's a big misunderstanding about how exactly and to what degree consoles or systems, be it handhelds or not, are banned in Mainland China.