Mutations

Natural Weapons

You posses claws, horns, hooves or sharp teeth that count as simple weapons with which you are proficient. On a hit, they deal bludgeoning, piercing or slashing damage (your choice) equal to 1d6 + your Strength modifier on a hit. If you aren't wielding any weapons or a shield when you make the attack roll, the d6 becomes a d8.

Improved Natural Weapons

The damage die for your Natural Weapons mutation increases to a d8. In addition, attacks with these weapons count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.

Hungering Weapons

While you take the Attack action on your turn and attack with your Natural Weapons mutation, you can make an additional attack as a bonus action.

Maybe leave this one to the subclass features

Tough Hide

While you are not wearing armor, your base Armor Class is equal to 10 + your Dexterity modifier + your Constituion modifier.

Scrambler's Grasp

Whether with thick claws, dexterous feet or spider-like legs, you gain a climbing speed equal to your walking speed. In addition,

Aquatic Adaptation

Through mutations such as gills, fins, blubber or porous skin, you can now breathe in air and water and you have a swimming speed equal to your walking speed.

Deepwater Diver

You are now adapted to surviving in the deepest depths. You have darkvision out to 60ft and have resistance to cold damage.

Maybe split this into different ones not limited to diving