With different dice ya, your example of 3d6 for less intelligent on average but capable of being as smart as humans makes me think that it would also be fitting to try perhaps 2d8+2
My first draft for em then would be something like this, based on the feedback:
Drork for now as their name (Not so smart conflation of their inspiration of dryads/ent wifes and orcs written in my native language when I was first toying with an idea with visual inspirations partially inspired by the quite famous "space orcs" of certain british sci-fi universe)
STR - 4d6+10
Con - 3d6
SIZ - 4d6+10
INT - 2d8+2
POW - 2d6+3
DEX - 2d6
APP - 1d6
EDU - 3d6 (As they are leftovers of an invasion so their "education" is a bit weak?)
They are plant based creatures, but I felt it's not fitting for em to be able to survive without eating as they are quite active, though I toyed with somewhat roleplay ability of them going dormant for long periods of time by rotting themselves and sorta being innert like a tree.
Not sure if there would be any fitting traits? Maybe something akin to tough bark skin to increase armour by 1?
Their flaw at least one I had written down had been: Need to be active at all times, as periods of few days of doing nothing to stimulate them leads them to going slightly mad (which I guess could work with mechanic of sanity? Sanity tests if left non-innert with nothing to stimulate them such as fight, tinker, talk, etc?)
Purovians - Humans for the most part, so these are easy, just mostly normal human profile:
STR - 3d6
Con - 3d6
SIZ - 2d6+6
INT - 2d6+6
POW - 3d6
DEX - 3d6
APP - 3d6
EDU - 2d6+6
Granted, some would be survivors of fairly weird case of "bloody world war that worked like ritual of magical climate shift" thus was half contemplating doing something like - you get to do sanity test or gain some trauma from being veteran of that war but it leaves you with one minor magical power, but this is probably bad idea.
Disposer - Sorta alien that just appeared at random, these people being where they always been perhaps (in truth they are just sorta people off another world with their own little story), but ya, lizard like some, others more human, so perhaps these should have few limitations on professions for sure (their original draft was: pile of artists, flesh shapers, mad doctors, schoolars and sorcourers stuffed on an island taking care of the dead of slaver island chain where nothing rots propertly, so they got mad artists and scientists feel to them).
STR - 2d8
Con - 2d8
SIZ - 2d8+2
INT - 2d4+10
POW - 3d6
DEX - 3d6
APP - 3d6
EDU - 2d6+7 (This covers their weird nature of being sorta band of mad scientists and schoolars)