My friend traded me a Mew recently that he got on his Pokemon Black game. I'm not sure if it's legit or not, because he won't tell me where he got it. All he said was that it was a really strong Pokemon and that I was in need of one. It has a Cherish Ball, but I'm not sure if he hacked it or not. Help?
If it got it in Pokemon Black, it's not legit. There has not been a Mew event since Gen IV, and Mew is an event only Pokemon.
However, if he transferred it to Black from an older generation, then it's possible that it is legit (Mew events given out in Gen IV were all in Cherish Balls).
To be honest, if it was legit he would have told you he got it from an event. The fact that he's not telling you where he got the Mew makes it seem shifty.
Mew - events
It's probably hacked. There is no way to get Mew in Black, so unless he traded it over it is hacked. It's in a Cherish Ball, but there have been no events for Mew in ages....I'm 99% certain that Mew is not legit.
It's hacked. The only way that anyone could possibly could get a Mew without hacking or waiting for the event is to obtain it from Pokemon Ranch from Wii Wares, so I've heard anyway. I doubt the Mew would be in a cherish ball, if he obtained it via Pokemon Ranch. I assume the cherish ball is only for event Pokemon.