As a weasel, your physical strength is limited. If your strength stat is above 15, apply the excess to your dexterity or charisma stats. You may choose to divide this amount and apply some to both stats, as well. You may exceed 20 points only in dexterity up to 23.

If your strength stat is 15 or less before modifying stats, add +2 to dexterity and +1 to charisma. You may not exceed 23 for dexterity and 20 for any other stat.

Your character can speak, read, and write Common as well as one other language of your choice.*

*If your character was Awakened or otherwise brought to a sentient state by a separate sentient being that speaks a language other than common, the language it speaks is your second language.

While you cannot speak to or understand other animals without casting a spell like Speak With Animals, you can communicate basic ideas and interpret simple responses with animals you interact with. 

You are a beast.

You are Tiny.

Because of your small size, you cannot use standard weapons with the exception of daggers, darts, or blowguns, and you cannot wear standard armor. You can have custom weapons and armor made for 1.5x the normal price of the item. You deal the same amount of damage as a standard weapon and gain the same AC bonus for armor, despite being small.

Your walking speed is 30 ft. 
You have a burrow speed of 25 ft.
Your swimming speed is reduced to 10 ft.

Your sense of hearing and smell are finely tuned. You have advantage on perception checks that require hearing or smell.

You are extremely difficult to hit when facing creatures larger than you.
When a creature of medium size or larger makes an attack roll against you, they have disadvantage. 

Creatures with a size of Huge or larger have advantage on attack rolls against you.

You can squeeze into any space with an opening of 1 inch by 1 inch.

If this opening is obstructed, you cannot fit unless you remove the obstruction.

Any opening smaller than 3 inches by 3 inches is considered difficult terrain, and your speed is halved while squeezing in areas of this size.

It takes 1 action to squeeze through a space and 1 bonus action to attempt to move/avoid an obstruction.

As an action, you can perform a weasel war dance to distract and stun targets. All creatures within a 10 ft radius, with the exception of allies, are targeted by this ability, and the target(s) must succeed an intelligence saving throw with a DC equal to your charisma modifier + 10, provided they can see you. On a failed save, the target(s) have the stunned condition until the end of your next turn.

You can only use this ability once per short rest.

You are naturally equipped with means of defense and offense.
Your tough skin and thick fur grant you an AC equal to 12 + your dexterity modifier. 
Your teeth and claws deal 1d4 + your dexterity modifier as unarmed attacks. You are proficient in your bite and claw attacks.