I would be interested in a Golduck evo, but maybe there would be an alternate evo to Psyduck? I'm pretty sure that the Slowpoke/Psyduck families are related (like Electabuzz/Magmar) and Slowpoke has two potential evolutions by level-up and by trade. A Jynx evo would make sense, but I'm not sure about it. I suppose it's plausible, at least, though Ice and Psychic are regarded as some of the worst defensive types. There're a lot of lines that deserve evolutions.
I wouldn't equate Special Attack with intelligence as something like Fire Blast wouldn't require that, although stuff like Psychic would. I always figured Amnesia raised Special Defense because it cleared the mind etc. I don't think any of them necessarily represent one singular thing.