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Love or Dream Ball would be awesome. Either/or, but preferably one that's a spitback, or alternatively I'd take any Ralts that has good IVs and a Knock Off Tutor move.
Flawless if possible (though that probably won't be possible due to my requirements of 31/31/31/x/31/31 and jolly for a Gallade build), Female if anything but flawless, ability doesn't matter, and my preference is really any exclusive ball, so you can decide whichever.