>>38163734Because Gamefreak though about type bloat for a fraction of a second and how there would be too many Water/Psychic types, even though they let it go for Normal/Flying, Rock/Ground, and Grass/Poison, and just Poison types in general. Even after realizing they were being hypocritical, they left Golduck as is out of sheer laziness/incompetence.
Starmie should have been the pure Water type and Golduck should have been the Water/Psychic. Starmie still would've been an excellent choice without Psychic, but Golduck could've really used it. Prove me wrong.