This technique brings your attention to the exhale part of the breath. Whereas we usually concentrate our efforts on the active inhale and let exhale escape passively, this pattern is reversed in kapalbhati. We exhale forcefully, engaging our abdominal muscles and let the air back in passively. This creates a cleansing and stimulating effect, but could be very energy consuming, so it is important to start small, at your comfort level before taking your practice further.
Because this exercise engages belly muscles, leaving alone chest muscles and the diaphragm, strong abs would come in handy. You do not need to have a six-pack, of course, but core training exercise would make the practice progress faster if you choose to take it to the next level.
Plank is a simple and easy pose which could help you train the whole core.