Indeed, don't forget that he also allowed the Main to train Feedback and get it into Vengeance. Plus, he allowed the Main to learn protective shields- something that is also not a trivial matter. The only attacks which Hellion didn't really help with were the attacks that were installed on Flint by Helena.
I agree that the Nameless One has knowledge of all the elements and I suspect that he's been exposed to all 4 of them. For instance, as a veteran of the Shadow Wars, he likely originated from the Psy Academy, where they teach Heat and Light attacks. Most likely, he saw the Shadowlings in action, and got experience in the Shadow element. Then, as the Psy Academy sided with Spriggats and Grtotius introduced the Cold element to the Psy Aacdemy folks, the Namless One could get a theoretical handle on the Cold element as well.