How is Knuckles retarded?
>knows how to set up complex boobytraps
>knows every hidden route of Angel Island
>knows ancient languages
>knows Tikal's grandmother's chant
>excellent with directions
>martial arts master
>the best treasure hunter on the planet
>knew about hotels, casinos, and other popular city attractions before the events of SA1, despite being on or near an altar for most of his life
These are not the qualities of someone with a sub-100 IQ. Hell, I'd say he's smarter than most of 4chan.