You need to have the affinity. Tsunade has four nature types. Sakura has 2. Not sure about Kakashi. You also need to be from a specific clan to use their techniques.
This is partially incorrect.
Anyone can use the clan jutsus like expansion and mind transfer; it's just that the jutsus are "hidden" and kept as a clan secret as to how to use them. They aren't like kkgs.
Also, it was stated that each ninja has just ONE affinity; their natural element, but can learn to use more but it takes years of training to learn to use them, and more years to master them. Anyone can use five natures, it's just that it takes a very long, usually too long, amount of time to do. Like when naruto was told that to master wind style to a respectable amount would take him years and years even though it's his affinity.
Only "geniuses" can master all five in their life time, like the third hokage, even if he was still weak.