>>30335424First thing off, you traded for an evolved dark-type known for having an aggressive streak that you had absolutely no prior relationship with. That's a pretty stupid move on your part.
Best thing I've seen done in such cases is to appeal to its sense of superiority - it believes it's the strongest around, so with no competition, it does as it pleases. Please don't tell me it's your only Pokemon, as one of the best things you can do is consistently battle your new Zoroark into submission over and over again, treat its wounds personally(this is important, don't take it to a Center over and over again), and try to reassure it that you can help it grow stronger if it LISTENS TO YOU and stops vandalizing everything.