What about poison and disease? The Poison Frog has a poisonous bite but no indication that it's immune to its own or that from other Poison Frogs. The Poison rules do not make any such mention either.
Should I assume two Poison Frogs fighting it out would poison each other with their bites? Also, a Poison Frog biting itself (it's, um, a little crazy) would poison itself?
Abilities of interest: Poison, Disease, Curse, Elemental damage, Petrification
Creatures of interest: Oozes (with acid attacks), Mummy (mummy rot curse), Basilisk/Medusa