Heh, sad how many of these commenters don't seem to realize that the Escapist News Network should be taken about as seriously as The Onion.
About the only bit of sex you'll find in Pokemon in Japan that you won't in the U.S. is Dawn's panties (her tiny miniskirt conceals not at all in a variety of situations) and the beach episode (apparently James crossdressing for his disguise (including flaunting his fake breasts) was considered too disturbing).
That's probably more than you'll find in Digimon (censored bits are about this innocent [http://www.youtube.com/watch?v=h04aECxONPc], and a bath scene which was also pretty kid friendly [http://www.youtube.com/watch?v=nsadGRYZD50]) or Sonic (where sex might be employed as a sight gag [http://www.youtube.com/watch?v=yGWBa6t9msY] or one-liner [http://www.youtube.com/watch?v=M7Zf1-2Ov1o], at most).
I'd be slightly surprised if Mario Party localization involved changes to anything other than translation - maybe if they had some sadistic mini-games like from a Japanese gameshow.
While nudity isn't quite as taboo in Japan, it's a common misconception that they're looser about sex. Actually, they're even more uptight about it than we are in the states, and much of what you see in their media has to do with relieving that greater level of societal repressed emotion.
