You know what Mew's abilities should be? Inconsistent and/or Mischievious Heart. Would be most broken thing in existence.
And I mean really, Smeargle gets Inconsistent and reading the freaking power of Inconsistent, being able to pass any of those boosts would be annoying as hell.
But an Inconsistent or Mischievious Heart Mew...so broken in a Heartbeat but it supposedly HAS THE DNA OF ALL POKEMON and things like GLALIE, OCTILLERY, AND BIBAREL GET IT AND NOT MEW?
Course, I would fear to see Mew get those but it makes far more sense as abilities than Synchronize. I mean, it is supposed to be the Ultimate Team Supporter and it is Mischievious, it should get the Heart and because it is Mew, it has Inconsistent Movesets to mess with because of unpredictability.
Oh silly Gamefreak, making such broken abilities and giving them to obscure Pokemon and making other ridiculous things and screwing us all. But then again, special ability Mew would probably be the ultimate troll of all. (