I would not call placental reproduction 'normal' simply because it's the way all mammals breed (with the exception of marsupials).
I belive the word you meant to use was 'camp'.
Rugurgitation is nothing to do with hermaphroditic reproduction.
Mini-rant over, I think it's about time I lent another hand here. Of the 38 Oddworld species known to us, we know, with certainty, the reproductive system of 9 of them:
Glukkons and
Mudokons both belong to super species of which there is only one queen.
Sligs are also a super species, but there is no confirmation that Skillya is the sole queen. Each hive of
Bees obviously has it's own queen.
Vykkers are hermaphrodites and reproduce by impregnating themselves (unlike worms, in which two mating partners both get pregnant).
Gabbits,
Elums,
Scrabs and
Paramites all have 'males' and 'females', although the precise means of reproduction is unknown. Scrabs and Paramites apparently lay eggs, since they have nests. Gabbits also lay eggs, which give birth to the tadpole form of the species.
We can also guess at a further X species and support our claims with evidence:
Bats, being mammels on Earth, might also be on Oddworld.
Fireflies,
Birds and
Fleas, too, may or may not be similar to their Earth counterparts. Alf has claimed the it is highly possible that
Slogs have queens, while, observing that they are absolutely everywhere on Oddworld, we can say that
Rats either breed with each other, possibly with themselves, or that there are a lot of queens.
Elderlings are slightly different in that they begin their existence as Elder trees, and elder trees on Earth use pollination to fertilize seeds. But then, if we're going to start talking about all Oddworld plants, such as Cacti, Virgin Saplings, Grass and SpooceShrubs, then we might as well start another topic.
Please note:
DO NOT start another topic specifically on plant reproduction. If you want to know, just look up on the net or in a book or a scientific magazine. You'll find the answer somewhere.