>>31529403Carbinks might be fairies but they have like no attack stat whatsoever (they can OHKO both these predators but they need investment, something wild carbinks probably don't even know about).
Those blue gems on their butts can probably come off quite easily if a sableye pulls hard enough or if a gabite cuts a slice of it, meaning they can take the risk of being moonblasted to death when a delicious-looking diamond is at stake. They also probably target the baby carbinks that are slower, weaker and easier to eat (I'd assume).
Think of it like lions and elephants. An adult elephant can kick a lion's ass and trying to hunt one is a massive inversion of energy and risk for lions, whereas they could relatively easily kill a baby elephant that wanders off on its own.
I guess the purpose of diancies in nature is to protect their carbink kingdom similar to what tsareenas do for their bounsweet.