I wacked 12 of them (3 large adults) and 1 female with 9 babies - blut trama over their heads with a spade shovel works great.
No matter how much coop upgrading you do - unless your coup is made of all metal (even then I've seen them pry and bite through mesh. They'll also naw through boards...
I woke up early this morning to hear my chickens in terror. In my boxer shorts and tank top, I went outside and saw 3 huge possums trying to get my chickens so I grabbed my trusty spade shovel and started whacking away. I felt somewhat like the guy from slingblade or a zombie film survivor...