Walkthrough: Connected to Route 15 is Route 16, a small route with few Pokemon and Trainers. It will lead to Ula'ula Meadow, which will take you to Route 17 and then Po Town.
Zygarde - From Dexio & Sina After Defeating Pokemon League
Island Scan Pokemon:
Prinplup
Wild Pokemon:
initial Pokemon - Daytime (Levels 32-35): Pelipper(30%), Scraggy(30%), Slowpoke(20%), Gumshoos(20%)
initial Pokemon - Nighttime (Levels 32-35): Pelipper(30%), Scraggy(30%), Slowpoke(20%), Raticate(20%)
Surfing (Levels 32-35): Finneon(40%), Tentacruel(40%), Pelipper(20%)
Surfing SOS Pokemon #1 (Levels 32-35): Lumineon, Tentacruel, Pelipper
Surfing SOS Pokemon #2 (Levels 32-35): Finneon, Tentacruel, Pelipper
Berry Trees (Levels 32-35): Crabrawler(100%)
Trainers:
Scientist Reid - Level 35 Charjabug, Level 35 Muk
Preschooler Kindra - Level 34 Mimikyu
Team Skull Grunt - Level 35 Trubbish
Items:
PP Up - Near Scientist Reid
TM81 - Near Aether Trailer
Comet Shard - Show Fisherman Pokemon With Tickle
Moomoo Milk - From Barista After Defeating Team Skull
Pecha Berry - Berry Tree
Persim Berry - Berry Tree
Aspear Berry - Berry Tree
Oran Berry - Berry Tree
Sitrus Berry - Berry Tree
Lum Berry - Berry Tree
Zygarde Cube - From Dexio After Capturing Zygarde & Defeating Him In Battle
Pearl (Hidden) - On Beach
Normal Gem (Hidden) - Northwestern Beach
PokeMart (Throughout Game Progression):
Poke Ball - Great Ball - Ultra Ball - Potion - Super Potion - Hyper Potion - Max Potion - Full Restore - Revive - Antidote - Paralyze Heal - Awakening - Burn Heal - Ice Heal - Full Heal - Escape Rope - Repel - Super Repel - Max Repel - Honey - Poke Toy - Adrenaline Orb
Post Game
Details: After defeating the Pokemon League and then capturing Zygarde in Resolution Cave, you can return to Route 16 to battle Dexio in order to obtain the Zygarde Cube.
Trainers:
Pokemon Trainer Dexio - Level 63 Espeon, Level 63 Raichu, Level 63 Slowking, Level 63 Metagross, Level 63 Alakazam, Level 63 Zygarde