In the cartoon, and I believe also in the comics, Harley's received a power-up from Poison Ivy making her stronger and tougher than the average human being, and immune to poisons. Is there any indication that she has that sort of enhanced capabilities in the Batman: Arkham franchise of games?
This in part came up because I was going to comment on an answer to Does Harley Quinn ever have children? that employed references in Arkham City that her enhancements might prevent her from having children, as is occasionally the case in serious takes on regenerators, namely that their body might only recognize a developing baby as foreign tissue and thus "cure" them of it.