Say I'm building a Transmuter wizard who is going to specialize in melee combat through polymorph spells like monstrous physique and beast shape. If I take a level of monk or unnarmed fighter to get Improved Unarmed Strike and then take the Dragon Ferocity feat, can I use Dragon Ferocity with a polymorph shape's natural attacks?
THIS RULE says Unarmed Strikes do not count as natural weapons, but do natural weapons count as unarmed strikes? The Fighter weapon groups seem to think so.
Natural attacks and unarmed strikes are separate. I believe you are looking for Feral Combat Training.
Feral Combat Training (Combat)
You were taught a style of martial arts that relies on the natural weapons from your racial ability or class feature.Prerequisites: Improved Unarmed Strike, Weapon Focus with selected natural weapon.
Benefit: Choose one of your natural weapons. While using the selected natural weapon, you can apply the effects of feats that have Improved Unarmed Strike as a prerequisite.
Special: If you are a monk, you can use the selected natural weapon with your flurry of blows class feature.
Natural attacks are not unarmed strikes. You would need the feat Helpful Harry helpfully mentioned to use Dragon Ferocity with natural attacks.