These are not the Chinese athletes you’ve seen on TV, those scarily synchronized divers or the gymnasts plucked from preschools for their bone structure. The Ultimate Frisbee players running and diving all over these fields are too scrappy, too goofy and having way too much fun. Ultimate Frisbee (often called just Ultimate as “Frisbee” is a trademarked brand) is growing in China, and 17 teams gathered here in Beijing for the national championship in late May.