Well I wouldn't be adverse to One Direction contracting anything that would keep them all off the world stage forever. I'm tired of them being referred to as a "supergroup" as well.
Koalas are just ornery and disgusting creatures.
We have plenty of possums here, don't you worry about that! If you have an animal that is habitat dependent and generally keeps to itself in bushland areas, then that will be your equivalent of a koala. Koalas don't nest in your roof like a possum will.