One thing I feel I should add onto this is from what seems to have been proven SRing and evolving can result in different abilitys upon evolving so if it changes to the other in one evolve just SR and try again (or so I have heard)
This should be false even without checking.
The ability, gender and nature of a Pokemon all depend on a 32-bit variable of the Pokemon called the PID. The reason why Pokemon that had only one option for their ability in ADV sometimes change their ability to the new option in DP is that their PID was pointing to the second ability in ADV, but since that Pokemon only had one ability at that time, only the default one was listed. When it's transferred to DP, the ability is recalculated from its PID when the Pokemon evolves, which would then display the second one.
In short, soft-resetting before evolution wouldn't help, since the ability is not generated at random, but from that Pokemon's PID which was set in stone at the moment it was generated (either when its egg was created or when encountered in the wild).
Also, Pokemon don't change gender when evolving after being transferred from ADV to DP, and don't change their natures, either. Gender and Nature are calculated also from the PID, and hence cannot change. If DP had new natures (or maybe new genders!), this could have happened, but no new natures were introduced in DP, so it didn't.