All of them:
Matt has done some amateur (non-ballroom) dancing and during Blue Peter, some Latin (paso and jive) dancing
Kara did some ballet and tap as a child and did the samba for Sport Relief
Pamela has listed a wide range of dances that she has some experience in - quoting from her guardian article:
"However, when it comes to dancing, I've had a reasonable amount of experience, through Scottish ceilidh dancing and the odd bit of hoofing when I was an actor. I was sent to ballet classes at the age of five to strengthen my limbs after contracting polio. I developed a passion for it, and continue to prefer barre exercises to a boring gym workout.
But I am most fascinated by the anthropological aspects of dance – its history and development in various cultures. I briefly studied Balinese dance in Indonesia and, during a recent stay in the South Pacific, learned to dance the Samoan taualaga. My current passion is for the social forms of Latin dances popular in my New York neighbourhood – the butt-shaking, passionate ones such as the bachata, meringue, salsa, and the Argentinian tango."
http://www.guardian.co.uk/tv-and-rad...ing-contestant
It's not clear how extensive any training she has had might have been.