Most of the Fuana [Untamed "Animals" of Oddworld] survived for ages before Industrialism crept in from the dark corners of the world, and continue to. Thusly, I'm going to guess that all "Mindless" beasts (Scrabs, Paramites, Slogs, Elums, etc.) and such would survive fine.
Glukkons would be the first to go. Years of lack of reliance has caused them to develop vestigal legs (Or perhaps mold, like Chinese footbinding). This disadvante would cost them heavily if forced to turn to their own devices.
Sligs might survive. As they do engage in work and labor (albeit, morally dubious in nature), it would seem more prevailant that they have always had no legs, and that they had adapted to that mode of living. It would be hard to get back to their roots without pants (previously provided by the Vykkers and the Magog, but not anymore
), but I reckon they'd survive.
Vykkers are harder to predict. They'd most assuredly perish in the wild without technology, but if given sufficient resources, I fancy they'd construct what they needed themselves. Their medical skills would ensure longer lifespans and disease care, and technology would enable them to fashion weapons. Hardley the defenseless overlords that the Glukkons are, but slightly handicapped by the lack of good help.
Interns...well, "Not even Interns think Interns are smart." They've been deafened by their rock music and stoned on pharmaceuticals. Suffice to say, their drive to survive is shot, even if they could beat withdrawl.
Mudokons have been living in the natural world secretly for years, without help or acknowledgement from anyone else. Suffice to say, they've already proved their prowess at living alone.
Gabbits, not so much. Remember, Munch's species was hunted to the brink of extinction. Not such a hot track record there.
Steefs, although strong in will and build, have been pushed to the brink of oblivion (or so it would seem), so far as that many locals think they're only the stuff of legend. Would they survive on their own? Depends on the competition.
Clankerz would suffer and die, slowly. Actually, I have no idea for them, but I'd like to think as such.
Grubbs problems don't seem to arise from lack of contact with other species, but from the exact opposite. I fancy that if they were left alone, they'd flourish better than they currently are.
Outlaws and Wolvarks are both rather standard races - two arms, two legs, and rather resiliant bodies. They've also demonstrated a pechant for taming wildlife. Suffice to say, they'd do fine.
Sekto's species ,whatever it's exact name might be, relies soley on hosts being plentiful, or at least available. Without their fellow species to captain, they'd be reduced to rather intelligent bottom-feeders. Nothing more.