You do realize the only way you can get this move is not just through DexNav but breeding as well.
Then again, Brave Bird is better off because Pidgey has a much higher attack than Special Attack and has 100% accuracy. In addition, since Ledyba has more Special Defense invested compared to physical Defense, I would figure that move will be preferred over Air Slash. However, the downside to Brave Bird is the massive recoil output despite those foes having low HP.
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