Well, aren't you the lucky one! :D
I AR'd Mew, Celebi and Jirachi and, as far as I can tell, only Mew won't obey. I'm not counting Ho-oh, Lugia or Deoxys because I obtained them through a Magic Door code rather than a plain encounter code. I've been training my Celebi up, but haven't tried fighting with it. As for Jirachi, I just wanted it to finish my pokedex off.
Again, as far as I can tell, if you obtain Mew with an encounter code, it will not obey you. I'm even having trouble trading it ( see the steam whistle from my ears). As I've said elsewhere, this has demoted my Mew to nothing more than an HM slave.
I haven't tried gamesharking or xploding for Mew: mainly because the codes are so long, they take time putting in, and the longer the code, the higher the risk of glitching the game. I get enough Glitches as it is!