Your Charisma score increases by 4, and your Constitution score is reduced by 2. Everyone loves Balloons and therefore they are extremely Charismatic, Children especially love Balloons, but Balloons tend to pop very easily and therefore have a reduced Constitution. 

Balloons usually live for around 12-20 hours.

Balloons tend towards Lawful Good alignments.

Balloons can vary in size from 12-90 cm, but average 11 inches or 28 cm.

Balloons are unable to walk but can levitate at a slow speed of 5.

You can read, and telepathically speak Common and one extra language of your choice.

Balloons will pop if they take Slashing or Piercing damage, count this as death. However a balloon is resistant to all bludgeoning damage.

A balloon may not hold any items because they have no arms. A balloon may wear a hat or helmet.

You are a balloon and enemies will not attack you on sight because they do not feel threatened by a Balloon, you receive advantage on all Stealth and Deception checks as a balloon.

If your balloon's AC is lower than 20, you may use 20 in place of that AC.