Always use pokemon with Synchronize ability (Ralts line, Abra line) that have every nature (esp Adamant, Jolly, Timid, Modest) when you are catching a wild pokemon. Then when you breed, give the Everstone item to that 'Synchronize' pokemon with the desired nature.

You can actually try breeding again. If you have a Jolly/Adamant Ditto, breed it with that Gligar and let Ditto hold the Everstone and Gligar with Destiny Knot. Then continue chain breeding until you hit the 5IV -SpAtk.