Since so many of you mention "be realistic", may I get to know what Marsupial species are considered as realistic in the aspect of zoos outside of Oceania. It looks like Tasmanian Devil and Wombats are not that realistic, are Eastern Quolls realistic if the fantasy zoo locates in Europe?
Wombats are relatively available in Europe. Though rare, it's good enough to be considered realistic in a fantasy zoo.
Tasmanian devils are doing quite bad in Europe right now. A few zoos have them but only small groups or single individuals.
Eastern quolls don't have that many holdings but Leipzig has a huge group and is almost factory producing them at this point, having almost 10 young every year.
Koalas in Europe have been having difficulty breeding and are becoming rarer, but the Netherlands is receiving multiple pairs from America in a few months.
Other than that, Possums, Bilbies and Bandicoots are essentially not to be found except for Brush-tailed possum and New Guinean ground cuscus. A few others can be found but with only a single holder.
I suggest checking the website "Zootierliste", they keep check on all the animals in Europe