>>55289594So my weird headcanon is this:
Corphish were introduced from another region accidentally and got out of control, so in response the people of the time brought over the original Psyduck, a Psychic Electric type to take on the Water type Corphish, and they were so good at it, eventually Crawdaunt started evolving the Dark type to take on the Psyduck. That pressured them into losing their Psychic typing (and eventually lost their electric typing through atrophy). Psyduck get headaches that are super bad because they only really recently lost their Psychic typing and didn't do a very good job of it, so it causes brain pressure
