The kata or forms contain all the movements of the system. Within each kata are the individual techniques that are practiced one on one. If an attack, multiple or knife is not in the kata, it probably isn't practiced in class. Classical stylists don't usually spar and when they compete it is in the forms division of the competition. Some classical styles, such as Goju, start out teaching the blocks, strikes and kicks of the system, teaching the grappling techniques in the higher forms.
Many people choose a style because the school is close to home.
Others choose a style based on monthly dues. You may pick a particular style because a friend is already training there. Maybe the college or YMCA had a particular program available. For any of these reasons you may have no idea what other styles are. If you are looking to join a martial arts and you have several classes to choose from, remember, from a self defense point of view, all styles have their merits, but there is a lot more to consider than self defense.