Here's a rather decent catching Smeargle for S/L. If people want, I can try to provide a few once I get one set up. The following is for those wanting a Jolly Solgaleo/Timid Lunala.
Smeargle @ Leftovers
Ability: Own Tempo
Level: 57
EVs: 136 Spe
Jolly Nature
- Night Shade
- Spore
Of course your fainted synch goes first in your party. When Smeargle hits the field, use Night Shade or Spore, if Solgaleo/Lunala moves first, confirmed 31 speed (or 30 speed or speed tie...). After the speed check, you'll want to use Night Shade a total of 2 times, if the health bar hits yellow, then you have less than perfect HP. Otherwise proceed to catch it.
I have yet to personally test this, but it should work.
For reference, Jolly/Timid max stats for:
Solgaleo @ Lvl 55: 232 HP/ 172 Atk/ 139 Def/ 131 Sp.Atk/ 119 Sp.Def/ 140 Spe
Lunala @ Lvl 55: 232 HP/ 131 Atk/ 119 Sp.Def/ 172 Sp.Atk/ 139 Def/ 140 Spe