I had a thought a minute ago. There have been numerous discussions of strategies in double battles with Skill Swap, such as using it to remove a Slaking's Truant to create an absolute titan. But what about using it to give Wonder Guard to a Sableye? No type of attack can be super effective against a Sableye without the use of very rarely seen moves (as it is Ghost/Dark), so if a strategy to get that ability onto a Sableye during a battle could be used, wouldn't that make Sableye essentially unstoppable (barring a Skill Swap or Foresight from an opponent or Sableye running out of moves to use)?
Something like that would be absolutely huge if it could be pulled off...