Is it possible for a creature like a bear to make an attack that counts as an unarmed attack, even though it has a claw attack as a Natural Weapon?
Yes. A non-monk bear without Improved Unarmed Attack could throw a punch, and that would be an unarmed attack that used the typical unarmed attack values for a creature of the bear’s size, be nonlethal, and provoke attacks of opportunity. Because a punch “uses” the bear’s paw, doing so prevents the bear from using his claw attack. He may still use his bite attack, but at a −5 penalty.
It can reasonably be assumed that a wild bear would never do so, but it could, and more relevantly someone shapeshifted into a bear could and might even want to do so, particularly if that person had Improved Unarmed Strike to eliminate the AoO provoking.
If a bear was also a monk (or, again, more realistically: a monk turned into a bear), the bear’s unarmed strike damage would deal damage as appropriate for a creature of the bear’s size with the given number of monk levels. Moreover, the unarmed strike would not need to be a punch (e.g. a kick), allowing the bear to also use his claws (again, at a −5 penalty).
Some relevant information about monks with natural attacks:
- Multiple attacks with natural and manufactured weapons – note that unarmed strikes generally behave like manufactured weapons even though they aren’t actually manufactured.
- Beast Strike and Black Blood Cultist are potent
- Beast Strike and monks is a little weird though
- Flurry of Blows and natural attacks – note that I have linked my own answer here. It disagrees with the accepted answer; I have laid out my case for that disagreement in my answer. Do consider reading all of the answers there to have a more informed opinion.
Basically, claw attacks are, well, attack with claws. Usually, the "unarmed combat" term refers to "punching stuff with your fists", and bear may as well do it, through, it surely does not posess an "Improved Unarmed Fighting", so if you want to optimize it a bit, you may give your bear a 1-level monk dip:
Monks are highly trained in fighting unarmed, giving them considerable advantages when doing so. At 1st level, a monk gains Improved Unarmed Strike as a bonus feat. A monk's attacks may be with either fist interchangeably or even from elbows, knees, and feet. This means that a monk may even make unarmed strikes with her hands full. There is no such thing as an off-hand attack for a monk striking unarmed. A monk may thus apply her full Strength bonus on damage rolls for all her unarmed strikes.
Basically, this text grants us two pieces of knowledge:
Usually, a character may not and can not attack while full-handed (and some may rule that ability to use Natural Attack negates the ability to use that, let's say, arm for unarmed combat)
A monk may do this, even if full-handed, so even if the DM rules that "the bear may not stop using claw attack to just punch stuff", a MONK BEAR can do exactly that. Like, jam some dude in the teeth with its bear elbow. Awesome AND practical.
okay, basically it's just a post about monk bears now XD
While you already accepted an answer, I'd still give another.
It is true no rules as i know directly forbid unarmed strikes on a bear or the like. On the other hand, there is no direct statements to ensure one that animals can fight unarmed (even someone shifted or transmuted into an animal).
I'd personaly rule against unarmed strikes on a bear.
Animals newer use unarmed strike (even for grappling). So I assume they haven't it.
Brief clarifications on my point of view on animals and grapple:
There are two "types" of animals from the viewpoint of grappling: some hasn't Improved Grab and some has. First ones normally will not try to start a grapple and if they are grappled will try to byte or scratch you (i.e. attack with natural weapon with -4 penalty). Those who has Improved Grab use their natural weapon's (which the creature used to establish the hold) damage in place of unarmed strike damage. They also has previous option, of course, but will use it quite seldom, i think.
What about someone who "became" an animal by some means? Most common ways to do so are Alternate Form and Alter Self and their variants.
Alternate Form says:
The creature loses the natural weapons, natural armor, and movement modes of its original form, as well as any extraordinary special attacks of its original form not derived from class levels.
The creature gains the natural weapons, natural armor, movement modes, and extraordinary special attacks of its new form.
Alter Self says:
You acquire the physical qualities of the new form while retaining your own mind. Physical qualities include natural size, mundane movement capabilities, natural armor bonus, natural weapons, racial skill bonuses, racial bonus feats, and any gross physical qualities.
Unarmed strike is a natural weapon (with some special rules, but still it is). So I think you lose it, when you polymorphed/wildshaped into something that hasn't it.