How exactly would someone get a Magic Guard Clefable with Softboiled? O_o; Is it even possible?
Breed in 3rd Gen, but don't evolve it. Teach Cleffa/Clefairy Softboiled through FRLG tutor. Migrate. Evolve and hope that your ability changes. Theres a 50% chance it will.
Poke's that got a new ability in the 4th Gen have a 50% chance of changing their ability upon Migration+Evolution. Its different though if they already had 2 abilities. (Shroomish has a 50% chance of chaning to Toxic Heal in the 4th Gen after Migration and Evolution, but Lightningrod Rhydon will never change to Solid Rock Rhyperiorm, only Rock Head Rhydon will.)
Its because the game internally gives every poke a 1 or a 2 ability, even if they only had 1 ability. In the 3rd Gen, both 1 AND 2 Shroomish had Effect Spore. Now, in the 4th Gen, 1 Shroomish have Effect Spore and 2 Shroomish have Toxic Heal (or vise-versa, does't really matter.) On the other hand 1 Rhydon will have Lighteningrod, same as Rhyperior, and 2 Rhydon have Rock Head (or vise-versa, again doesn't really matter), while 2 Rhyperior have Solid Rock. The number doesn't change upon evolution.
So, if your Clefairy from the 3rd Gen has a 2 for its ability variable (idk what its really called), it'll change when you evolve it.
Wow. I wrote more than I thought I would.
Edit: And 2 people beat me while I was typing this :/