You can speak, read and write common. You can can communicate with koalas without trouble. You can communicate simple ideas with other beasts.

Koalas have many names mostly based on australian references, cities, or Aboriginal language. Many of these names are gender neutral, but are put where they seemed to fit.

Male: Bindi, Bobo, Digger, Fluffy, Kiko, Koa, Mellie, Tucker, Wally.
Female: Anku, Kirra, Kika, Nuara, Mel, Sydney, Kato, Kelly, Kira, Wagga.

Your Constitution increases by 1, and your charisma increases by 2

Magic koalas live longer than normal koalas. You can become about 40 years old.

Most koalas don't care. They tend to have an alignment close to neutral. Koalas only go evil very rarely, mostly due to magic or planar travel of some some kind. There are no cases found of koalas going evil without magic.

Koalas are very small, you can become 2-3 ft. long. Your size is small.

Koalas are small animals, that can sometimes run. Your speed is 20 and your climbing speed is 20. 

You can eat eucalyptus leaves, that would be poisonous to others. You have resistance to poison damage, and have advantage on saving throws against being poisoned.

Due to your magical ancestry, you can cast goodberry, but instead of berries, you spawn eucalyptus leaves. Only koalas can eat these leaves. If a non-koala eats them, the creature must succeed on a DC 10 constitution saving throw or be poisoned for 1 minute. You can also cast bless. You can use these spells once per long rest. You don't need material components for these spells.

You gain proficiency in an instrument of your choice. Preferibly a didgeridoo, if your dm allows a bit of homebrew.

Koalas are more dangerous than they look, especially magic ones. Your unarmed strikes do 1d4 piercing damage plus your strenght modifier, instead of 1.