I was wondering if it matters who gives the animals to a chao in SA2, to make a dark Chaos Chao. If a good person gave animals to a chao that evolved and is dark, would that stop it from becoming a Dark Chaos Chao?
First off, if the chao's already evolved, it doesn't matter who takes care of it as its alignment is set until it reincarnates. After that point, it can become any other kind of chao of any alignment regardless of what it was on a previous life.
Care given from a character will change the chao's alignment to match that of the character used, but only gradually - it would take extended amounts of care to actually affect its alignment. It's possible to have, for example, a hero-side character give an item to or care for a chao without it going hero so long as the chao receives most of its attention from dark-sided characters.

~ Crazy C Lea