i'm.... not sure how much they count as living exactly. Shiki being able to kill 'em doesn't say anything as the dude was killing zombies for a bit there. they aren't alive in the traditional sense - remember that Chaos as a whole is a giant reality marble encased in a body. effectively it's an entirely different world inside him and that's where his beasts reside, after he killed and/or absorbed them basically. their 'regeneration' isn't exactly them doing it in the traditional way either because any one of them can result in the rest 'regenerating' for that same reason. you can think of it as anytime they die they will always come back to the 'world' they're from. to that end, trying to do a take over would.... kinda make me think that they could also be forced back into it and possibly override said takeover as it's going back to a giant mass of blob. though that also brings up the other question of whether or not smith would still have his connection to 'em. if he did then things would get really weird as there's no individual sentient being inside. he's got some immortal and legendary beasts that should have high intelligence in there, so it'd be really strange of a scenario and absorption vs. absorption.
still, that's also really the only thing Smith has going for him. if he can't absorb/take over the beasts then he's pretty much screwed, can't kill the guy. i'm not sure Smith can even deal with the beasts that well either, or at least the high end ones. soil's a gimme for Chaos if he gets him, but that'd again gets us to absorption stuff.
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The King Wang.
Listen up Urinal Cake. I already have something that tells me if I'm too drunk when I pee on it: My friends. - Colbert.