Edd is son of Earth... at least one of earths, there's more Earths and earth children like him, so he common.

Warning: he will b!tch slap you if you make fun of his kind or treat him like a slave

Matt is son of Saturn, he's not most common but not rare either, what makes him  special is the value he has. Not a lot of his kind has a ring like he does
Warning: if you try taking his ring, it will return back to him, it can only leave his head for hour or so

Tord is son of Mar, least one of Mars. Just like Edd, there's more Mars and Mars children, he's the 2nd common.
What makes his kind different from Edd's  is his kind have to protect the other planets
Warning: harm his friends, he'll harm you

Tom is son of star, he's first child of the stars, so he's very rare and value
And also very dangerous. What makes him dangerous is the stardust he has in his eyes, that stardust can create biggest explosives which is the reason why all different army's are after him
Warning: if taken too much stardust from him, his monster side will be trigger in self defense.
If his stardust becomes unstable, he will explode

Judy is daughter of comet, she's rare (not rare as Tom but still rare), her kind have some stardust, not a lot but some. The stardust helps keeps her kind alive, the armys hunts her kind down and takes the stardust, because of that, her kind have to go into hiding which is why it makes her rare
Warning: she leaves trace of stardust whenever she flies, it can be messy and dangerous

(Drawings do not belong to me, only my oc one,
Anyway what galaxy child is your oc? Are they rare? Common? Value? )