There's something about Basculin I don't get. If it can learn Zen Headbutt, why is it unable to learn Iron Head?
The reasons Pokémon can and can’t learn certain moves is still pretty poorly understood! We might know more someday, but for now it’s mostly guesswork.
Basculin might have difficulty learning Iron Head due to propulsion issues! Psychic abilities wouldn’t really interfere with swimming, but steeling yourself would tend to make swimming a lot more difficult due to weight, buoyancy, and density issues! A Pokémon that’s already a Steel-type would be able to compensate for that, but it could be harder for a Pokémon that isn’t!











