Pokémon Sun and Moon - how does this even work?

Yesterday I was trying to catch a Carbink. It called for help and a Sableye came. But instead of attacking me the asshole attacked and KOd the Carbink I was trying to catch before I could get him. It just completely ignored me. I've never seen anything like that.

Also later I was catching rocruff and my munchlax KOd one and levelled up but the one that had come to help KOd Munchlax. But after the battle munchlax evolved into Snorlax despite being KOd. Man so much weird but cool stuff is happening in these games.

I imagine it attacked the carbink for the same reason zangoose and seviper will fight in X&Y. As a gem pokemon, it'd naturally be sableye's prey.

As for evolving, being KO'd won't affect it, if they reach the level they evolve. Always been that way.