But he'd have those powers the same way a "normal" person who's never been in training has the ability to fight... in other words, "not much." Several stories have shown that experience and honing his skills puts him at an advantage vs other Kryptonians (like the Phantom Zone villains). Just because you have the possible ability doesn't mean you know how to use it or know that it exists, let alone use them at the speeds that he can. Granted, writers don't always emphasize that, but there is a clear precedent for it. The New Krypton storyline actually had him training fellow Kryptonians/Kandorians because of his advanced knowledge and self-training over the years.