Wildshape

You may adopt the fighting style or (if using magic and able to cast spells normally) the actual form of an animal. It is an Action or Move Action to adopt the fighting style, and a Full Round Action to actually transform into the animal. Both useages of this feat may only use Unarmed for attacks (unless otherwise stated) and lose access to all other COMBAT FEATS (only) when in animal form.

Rather than taking a specific animal you take an archetype and choose feats. CL defines the benefits.

Each Archetype has a list of feats, a Stat Score (that you may choose to swap out), scaling base damage dice (different for those using magic and those using unarmed), and Armor.

Sizes are still restricted by CL, and only affect those who use magic.

Medium is CL 1, Large and Small is CL 3, Huge and Tiny is CL 7, and Gargantuan and Diminuitive is CL 11

reference following for bonuses etc…. https://www.d20pfsrd.com/gamemastering/combat/space-reach-threatened-area-templates/

Size increases or decreases your Armor bonus by 2 for each step outside medium. For example, a Huge creature would have a +4 bonus to armor (on top of any gained from their archetype), or a Small creature would take a -2 penalty to Armor (armor cannot go below 0).

You may also look at an animal from 3.5 and pathfinder and ask your dm if you may use a feat from that animal

Rather than having a separate HP bar, you still retain your own HP, and just gain armor

If not ACTUALLY transforming into an animal, you do not gain armor or the size increase bonuses, just the feats and the listed changes to unarmed damage (frequently none).

If NOT turning into an animal, gain an extra feat for every 4 CL

Feats That Can be Taken by Any Archetype
Nighteye (CL 1)- Suffer a -1 penalty in brighter lighting conditions, but suffer no penalties to sight in darker conditions.
Combat Reflexes (CL 2)- Make more than one AoO per turn (DEX or INT mod +1 total)
Additional Attack (CL 5)- Same as the normal feat
Deadly Maneuver (CL 5)- Same as the feat
Maneuver Specialist (CL 4)- Use a Stat of your choice for all Combat Maneuvers
Maneuver Mastery (CL 2)- Gain a +3 bonus to three combat maneuvers.
Ambidextrous (CL 1)- Same as the normal feat
Water Creature (CL 1)- You can breathe underwater
Amphibious (Magic Users Only)- You are amphibious
Charging Animal- Grants +3 STR and 0 DEX (+2 for every 2 CL above CL 1), 1d6 damage (+1d6 per 6 CL) unarmed stays the same, one feat plus one feat per 2 CL, and 1 Armor (increases by 1 for every CL).
Improved Charge (2 CL)- When you charge add +2 to hit and add an additional damage dice.
Maneuver Charge (2 CL)- As a Full Round Action you may perform a single combat maneuver (chosen when transforming into the animal, may be taken multiple times) along with a charge while still doing damage.
Armored (5 CL)- Gain an additional +3 Armor.
Overwhelming Charge (6 CL)- When you charge double bonus (+4 to +8) and double damage dice.
Devastating Charge (9 CL)- If you have multiple attacks may hit multiple targets with a charge.
Line of Destruction (10 CL)- As a Full Round Action move your full movement speed in a straight line. Anyone within that line must make a Defense Check against your attack roll or take damage from your normal attack.
Stalking Animal- Grants +2 STR and DEX (+2 for every 3 CL), 1d6 damage (+1d6 per 5 CL) increase unarmed by one size, 1 feats plus 1 per CL, and +1 Armor per 3 CL.
Enhanced Senses (CL 1)- Gain a bonus to Perception checks equal to your CL.
Sneak Attack, Improved Sneak Attack and Greater Sneak Attack (CL 2)- Works the same as the feats, each must be taken separately.
Pounce (CL 3)- If you are undetected prior to your turn during a combat round you may make a charging attack that does double your base damage dice. This may be combined with sneak attack.
Biting Attack (CL 4)- Your base damage is increased by one size for a single attack in a round.
Raking Claws (CL 4)- You may make two attacks for a single attack action (first attack only). These attacks suffer a -2 penalty to attack rolls and only do ½ Stat Mod bonus to damage.
Animal Strategy (CL 5)- When able to make a sneak attack, you may sacrifice the sneak attack damage (but not other damage) to instead complete a combat maneuver against the target.
Grabbing Animal (apes, etc)- Grants +1 STR and DEX (+1 for every 2 CL above CL 1), 1d6 damage (increase by one size every 2 CL) unarmed stays the same, 1 feats plus one per CL, and +1 Armor per 2 CL.
Improved Maneuver (CL 2)- Choose a single combat maneuver to gain a +3 bonus
Climber (CL 1)- Gain a bonus equal to your CL to all Acrobatics checks and Athletics checks to climb.
Skilled (CL 5) Choose any skill that isn’t from the Society Skill Group (you may choose a Craft skill though), and grant yourself a +3 bonus while in Animal Form.
Opposable Thumbs (CL 3)- You are able to awkwardly use tools, open doors, etc. You may only use your form’s skill (gained through Skilled) when making craft checks.
Warrior Ape (CL 11)- You may use weapons in your animal form, though you must use the Skill Mod gained from Skilled to make attacks.
Flying Animal (birds, bats, etc)- Requires at least CL 3. Grants -1 STR and 3 DEX (+1 for every 2 CL above CL 1), 1d6 damage (+1d6 per 5 CL) increase unarmed by one size, one feat plus one per CL, and you may have no Armor.
Eagle Eye (CL 3)- You gain a bonus to sight-based Perception checks equal to your CL
Flyby Attack (CL 4)- You may make a single attack before continuing your movement action (you may make an additional attack at the end of your movement if you have one available).

Sneak Attack, Improved Sneak Attack and Greater Sneak Attack (CL 2)- Works the same as the feats, each must be taken separately.
Divebomb (CL 6)- Spend a Full-Round Action to prepare for a(n aerial) charging attack. Move your full movement distance (in a round, 30 ft for most normal humans) at the target in a straight line, then make an attack as another Full Round Action with a +10 bonus, and if you hit increase your number of base damage dice by one for every 2 CL. This attack may be done as a sneak attack.