Below is a video that I recorded, sorry about the shoddy quality. http://www.youtube.com/watch?v=r0rEkxYGEuY This is merely an experiment to see how ability changes on Pokemon that have already set stats. This could work anywhere within the game, it will not work for gift Pokemon for the fact that you get it right away, nor will it work for Wild Pokemon since their stats will never stick, since well... they're wild. 0:00 Game is booted. 0:40 I bring up the Shadow Monitor, note that Rhydon has been seen already, as with Moltres, but not Greevil's other Pokemon, since I have lost on purpose. This means that Rhydon's stats are set and will always remain the same if I reload. 1:15 Lugia battle does not occur since I stole it already. 1:58 Manectric used Thunderbolt on Moltres, Rhydon has 2 Abilities, Lightningrod and Rock Head, since T-bolt did not get redirected to Rhydon, his ability now is Rock Head. 2:07 Game Reset 3:22 The same Rhydon again. 3:38 Manectric used Thunderbolt! Rhydon's Lightningrod took the attack?! Isn't this the same Rhydon? I believe that this glitch happens the same way how ability changes when you Pal Park Pokemon, if they evolve, their ability can change. Likewise, this is only reliable for Pokemon that can reach its final forms in 3rd Gen, so that their abilities can stay intact for 4th Gen. This can be especially helpful for Pokemon with a certain preferred ability and have an XD Move, such Rapidash, Dodrio, or Marowak. Aside from Greevil's Pokemon, if you want the Pokemon to have the chance to change its ability, Miror B. will have to have procession of it. This is only a guess, but I'm guessing this "glitch" occurs since for whatever reason, Genius Senority decide to put Ability Generation as a separate RNG as oppose to attach to the Pokemon's PID.