Many teams that I've observed use electric knives. For ribs, most people will cut ribs so that they cut along the rib bones next to the one bone in the center, instead of through the meat, to allow for more meat to be eaten by the judge. Pork can be sliced or pulled; brisket is generally sliced, but some teams cut the deckle/point into chunks a la burnt ends. Chicken is usually left whole as most teams submit thighs.
IMHO, the hardest thing to cut is brisket because it will have a hard outer crust, i.e. bark, but can be extremely soft when cutting through the point/deckle, and firm when cutting the flat. The hardest part to cut through is the bark.