Boys can actually compete in synchro skating so there are actually "mixed teams" (I remember that I once saw in a show an Italian synchro team where there was a boy skating, and one team also had a boy at last year's Worlds, I think)... But I would like to see boys synchro as well, it would be really interesting!
Russia's Dream Team. It's their free program from 2010. In the past they have had a team with 10 boys and 10 girls, but 7 is still quite an impressive number, 'cause boys are rare in synchro. That kind of "entertaining" warm up is also rare in international competition.
Canada's Nexxice have 1 boy, but they have done good job hiding him with matching costumes! SP from last year's Worlds
Australia's team Fire on Ice usually has boys too, last season they had 2.
Canada's senior Nexxice syncro team has one male member. They performed at the Canadian Nationals gala this year. However, I found their performance better at the SCI gala last year.