This is actually pretty cool. I still have a few curiosities, though:

Are entities attached to their stones like a genie to a lamp or something? Like, are they physically connected to it at all times and restricted by range? Can they extend from and retract to their stone? What would happen if the host and the stone were to separate, or if someone else took the stone?

Are entities' appearance and personality shaped by their host and/or stone, and if so can they be transferred to another host for any reason and consequently adopt new traits?

Are entities capable of physical interaction, and if so, what do they feel like? Can they fight or take punishment? Do their genitals serve a purpose, or are they there just for fun?

Sorry if I'm coming off as critical; that's not what I mean. I just think these are way cool and want to know more.

Perfect questions!

1. yes they are essentially attached to the stone much like a genie and can only stretch up to 25ft away from it before they need someone to move the rock. They can indeed extract and retract to their stone and even hide in it. Depending on the upbringing an entity will either develop separation anxiety if stuck to one host for a while, thus becoming a hassle when moved away from the host. Generally separating an entity from their host won't cause much harm but will cause it to act aggressive to whoever took it. They are unable to hurt their primary host but if taken by someone else can easily harm the person.

2. General appearance tend to be affected by their host and sticks (I.E Radio looks nothing like Chii and is bigger than Lucky) at times they might be shaped to their stone but this is only if they're the type that has the stone attached to the body, allowing them to move freely (I.E Tiger's eye).
Personality wise they do not take much trait from their host but often picks up small behavior like habits and so. (I.E Lucky liking sweets as Chii is a baker)

3. Physical interaction is possible! They vary from stone to stone. lucky feels smooth, sort of like fine polished leather, while Radio has a more cool temperature and the 'hair' on top of their head is soft. They are capable of combat and can be granted a maximum of three different forms (Regular. Fright and Fierce)... Their genitals can be used for reproduction but such is only possible if it's mating season for the other specie. They are usually not supposed to reproduce but it's possible although rare.

Awesome, thanks!
When I get myself an appropriate character, I think I'd like for you to help design an entity companion for them. They'd make a fun addition.

I'd be delighted to!