you just need skill, planning and a little luck. sometimes, you can chain attacks with jutsu then with specials. one example is temari. get a combo going and end it with an upward hit or throw. when she is coming back down, use her wind scythe jutsu. when the opponent comes down, press triangle and circle and if your timing is right, then your opponent will take quite a beating.
Also you could just give your opponent all stars on the option mode before battle*to lessen the damage you give them to get more combos before they lose all their health and also skill.