Quoted By:
>Smeargle @ Leftovers
Ability: Technician
-Flase Swipe/Hold Back
-Spore
-Recover/Milk Drink/Shore Up/Slack Off/Softboiled/Roost/Synthesis/Moonlight/Morning Sun
-Soak (for those pesky Ghost- and Grass-types)
This is the set I've been using since SoulSilver. That Smeargle has helped me catch every single legendary even in USUM.
Alternatively:
>Tapu Koko @ Leftovers
-Nature's Madness
-Thunder Wave
-False Swipe
-Roost
PROTIP: If you're ever trying to catch a Ditto, don't leave your Pokémon Center without one of these!
>Magikarp lvl 1
-Splash