Sorry if this breaks rules, I GENUINELY cannot tell what this site actually is, but if I am presuming it correctly, it SEEMS as though you can use this site to check if your pokemon have been hacked/could have been hacked.
https://www.pokecheck.org
I had a quick look around and it seems people could store, clone or otherwise use it to check pokemon they have. If you have a pokemon that you think is hacked, input the OT and ID No. (or just the ID No. if you can't read the name characters) and check to see if your pokemon has ever been on that site. Again, I'm not sure what the purpose of the site actually is, but if you're concerned your pokemon has been hacked, you go to that site and see that your pokemon is on it and it has been downloaded 523 times or whatever, it probably, at teh very least, has been cloned if not hacked. Plus you can also read a legality check at the bottom of the pokemon summary screen to see if it was likely hacked, RNG abused or what.
Once again, sorry if this breaks any rules (I'm honestly not sure if it does, because I honestly can't tell if that site is ACTUALLY used to cheat or if it's simply a storage site like Pokebank long before pokebank came out, or what it actually does, it's not very clear) however it's a good starting point to quell worries if your pokemon is hacked or not. Obviously not every hacked pokemon will appear on there, but the popular ones will (my Korean shiny Darkrai apparently was as it shows up on that site. The legality check said it was likely RNG abused and it had been downloaded hundreds of times) It's moot though since I traded that for my Arceus which was the movie event pokemon and that's listed on the site as well, so it could be simply a site to store pokemon for all I know. Again, not 100% sure what the site is actually for, so take what you find with a grain of salt, but if you're THAT worried about hacked pokemon, this may put your mind at ease a bit.
EDIT 2: NEvermind! ;-), the original post stands!