How do you know if you Pokemon is hacked?

Answer 1

Usually the apparent met level will be off, that is different than that of the true encounter level in game, it also depends on what hack may have been used to obtain it, a Darkrai that was obtained using an AR with the secret key item event cheat, will look totally legit and there is no way to tell, but if it was caught outside of that event, something won't be right about it. It should be noted that if your friend has an Arceus that was caught in the hall of origin, it is not legitimate, because it is impossible to have at this point, because the event that distributes the azure Flute hasn't happened yet, to my knowledge. Apart from that just look for things that don't seem right, odd catch ball, odd met level/date, or area, their stats may be really high if they are hacked too, look at their stats, just because they are legendary, doesn't necessarily mean they are bleeping invincible like stats 999 and the like. If the stats don't seem to fit the level of the pokemon, within reason, you may have a hacked pokemon. The reason that it is so hard to tell is why it happens, just don't trade your best stuff for a fake, no body likes a cheater who tricks another person into taking something fake for something good. In fact no one seems to like cheaters in general.