Just try taking each of those Pokémon onto Wi-Fi individually alongside some that you know are legitimate(ie. self-caught ones), to suss out the hack/s in your team.
You only need to do this with the Pokémon that you obtained in a trade though, as i'm sure you can vouch for the legitimacy of those you captured and trained yourself;]
If you get the message warning come up whilst testing them individually, saying that you are not allowed onto Wi-Fi with your current pass, then you've found your hack.
Shaymin, Arceus, and hacked movesets/abilities cannot go in wifi.
(Pokemon with more than 510 EV's turn into bad eggs, but some hackers apparently found a way to get through the ability filter. Well, at least they can't go in wifi)