Although Plato's Theory of Forms presents as a consistent, "scientific" system of metaphysics, it doesn't really hold up under scrutiny, and there's a strong tradition of thought that it was never actually meant to. Plato's philosophy in general is riddled with inconsistencies. Almost none of it is possible to follow through with in an rigorous manner, such as suggested by your question.
For quite a long time, the assumption was Plato was just getting things wrong, or being sloppy. That's largely how Aristotle and his followers took it, and it's still a live and popular view. But several centuries after Plato's death, a new school of thinkers, led by Plotinus, formulated the "Neo-Platonic" interpretation of Plato's work. Under this view (which I personally hold), Plato's mistakes and inconsistencies are deliberate. He's trying to explain concepts and ideas that he does not believe can EVER possibly be contained, directly conveyed, or fully explained in ordinary language. Instead, he's giving us an elaborate set of metaphors and analogies meant to guide us towards the Truth without ever embodying it.
In the Neo-Platonic universe, there's only one truly REAL entity, which Plotinus called "the One" but that Plato calls the "Form of Good." We might visualize it as being like the sun in the center of the solar system. In orbit around it are less real, less perfect copies of the Form of Good. Close in, and almost identical with the Form of Good are things like the Form of Beauty or the Form of Love. At a further remove are things like the Form of a Chair or the Form of a Banana. And all the way out here in the ordinary world, are even more degraded copies, like an actual chair or actual banana. But all those other "Forms" besides the Form of the Good are really just metaphors, things to lead you to thinking about the Form of the Good. Plato discusses them at length, but he isn't really committed to their metaphysical existence (at least not in this read). So the Neo-Platonic answer to your headline question is "1".