Return of the Dark Sorcerer

Shadow Flare should be cast in the same way Hidon did yes, once all the Metroids are dead. So yes he could have learned that, which is the most powerful Lore. Outside of that though, no, no Lore's are intended to be granted as a prize for finishing that quest, though it is a fine idea!

EDIT: I should say there are a couple other bosses that will cast it like AlphaOmega (Atma), but that is rather late and harder to get.