Kakuzu slightly tilts his head to the right, quite intrigued that both of his students know a considerable amount already.
Decent I guess. You already know a substantial amount about Ninjutsu, so let me further fortify your knowledge with my explanation of Ninjutsu and everything it entails. However, one thing you both failed to mention is that since Ninjutsu is a more primitive version of Elemental Ninjutsu, most techniques in this category are actually weak to all elemental ones. Few exceptions exist such as Rasengan, where the chakra is worked and molded with advanced shape manipulation, putting it on equal terms with elemental variants. Once you've read and understood the following, we will proceed.
Ninjutsu is the usage of chakra to perform various tasks which can't be performed otherwise. Its an extremely broad term and encompasses many things such as: weapon usage, medical uses, transformations and so on. Unlike Genjutsu, its effects manifest in reality and not solely in the illusonary. A notable user of Ninjutsu is the 2nd Tsuchikage due to his arsenal of highly regarded techniques. Through chakra manipulation alone, he could achieve flight through unknown means, turn his body completely invisible and "split" his chakra into two separate bodies. His splitting technique far surpassed conventional clone techniques as both halves of him are considered the "real" version of him, meaning they couldn't be dispersed.
Ninjutsu isn't solely based around chakra usage and performing complex techniques and maneuvers, but is also in reference to the skill set a ninja should possess. The term "Ninjutsu" literally means ninja skills, leading me to believe its actually a more abstract concept to what we first perceive. A ninja should be a keen analyzer of situations, capable of conjuring up plans, tactics and counters, both in the heat of a battle and in preparation for one. They must make proficient use of the various ninja tools at their disposal, using all of the utensils they possess to the fullest. Awareness is another very important skill a ninja should possess. Paying close attention to detail, making logical inferences about your opponent, gradually deciphering your opponent's fighting style, noticing minute disturbances in your surroundings and remaining vigilant at all times is required if a ninja is to survive. Often a lack of awareness leaves you prone to assassinations, being struck by invisible attacks or worse still, making you unable to realize nor release an illusionary technique.
Even with the astounding abilities a ninja can come to acquire, he/she should never overlook or forget these fundamental rules. It could very well result in their downfall.