yeah, i think it's widely available, but in general i think it's just too expensive for ordinary chinese.
also, it's in japanese, which makes the demand somewhat lukewarm. it's hard to get an english version, or even pirated copies of games in english.
i don't know what an official nintendo release would use english. probably probably.
online games are very popular. if nintendo is to make real money in china some kind of online game would be crucial to its success. but nintendo seems too conservative to pursue that kind of strategy.
the Wii is an epidemic.