Senseilou is correct but it also depends on your definition of martial art. As Senseilou notes the distinction between grappling and striking arts is informative here. Other important distinctions might be new/old and armed/unarmed. Many 'new' arts avoid kata (but use ippon or set sparring) largely because they are ecclectic arts that strive for a complete striking and grappling base. I would include jeet kune do in the 'new' catagory for this reason. Armed martial arts lend themselves well to solo collection of movements or katas. As far as i have seen unarmed European arts (pankras, wrestling, savate)do not use kata. It is importan to remeber that 'martial art' is not a title only reserved for close quater fighting systems of the orient. Once this is acknowledged it is much easier to understand the differences of opinion on training kata an forms. There is also the reality that grappling arts that do not lend themselves well to kata have proven to be some of the most effective ways of stopping an opponent.