I have a bear shapeshifter in my group... in bear form he has Inhuman Toughness... and it didn't make sense that there'd be a specific source of damage that's extra-damaging verses bears, hence, he shouldn't have a catch.
Nevertheless, as the book does require one (even when it makes NO sense), so we did some thinking- wereforms that are particularly big have to use Ectoplasm to bulk up- so if anyone manages to draw a circle around him, or bring running water to bear (no pun intended), the ecto will evaporate, allowing anything to bypass his toughness, and causing more than a little discomfort.
Not much of anyone's going to guess to put a bear that's attacking them in a river or a circle, so definitely unknown, and rare. Also, not easy to pull off. We ruled it a +0, and left it at that. It's a little bit of a cop-out, but only a little.
For zombies... fire, running water... *shrug* Similarly cop-outs, but it works for me.