Walkthrough: At the end of Poni Meadow is Resolution Cave, a place you might not visit on your way to The Battle Tree unless looking to find rare items in its Basement. Most player only visit Resolution Cave during the Ultra Beasts Storyline, where Guzzlord is found.
Wild Pokemon:
Initial Pokemon (Levels 54-57): Golbat(70%), Dugtrio(30%)
S.O.S. Pokemon #1 (Levels 54-57): Crobat, Dugtrio
S.O.S. Pokemon #2 (Levels 54-57): Golbat, Dugtrio
Trainers (First Floor Only):
Backpacker Maria - Level 57 Emolga
Hiker Travis - Level 56 Dugtrio, Level 57 Mudsdale
Zygarde Cells: There is three Zygarde Cells found in Resolution Cave.
Items:
Elixir - First Floor Near Mudsdale Path
Terrain Extender - First Floor Right of Backpacker Maria
Starpiece - First Floor Near Large Boulders
TM26 (Earthquake) - First Floor Left of Backpacker Maria
Adrenaline Orb - Basement Northwest Corner
Light Ball - Basement Southwest Corner
Big Nugget - Basement Northeast Corner (Hidden Item)
Life Orb - Basement Southeast Corner