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Use a Synchronize Ralts to pinpoint the nature you want. Faint it and stick it I the front of your party. Then use a Trace Ralts with a Smoke Ball. I've been able to find those pesky Hidden Ability Pokemon a lot easier with this as well as get good natures for breeding. This likely will cut your ball usage and time looking in half.

Example: Timid Synch Ralts I fainted in front of party. Go into a Electric Safari to hunt Helioptile. Then use the second Trace Ralts to find a female Helioptile with the ability you desire.

Hope you guys find this useful in your endeavors of finding your dream team of Pokemon.

Trace Ralts is great for HAs, definitely. B) I think it's easier to just catch a bunch of Ditto and breed than to sync though. Just my opinion