Walkthrough: In order to get to Po Town, you must start by going on Route 15 and head north. Luckily, the Unova Elite Four Member Grimsley will help with giving you the Sharpedo Poke Ride, allowing you to destroy the rocks within the waters.
Wild Pokemon:
Initial Pokemon - Daytime (Levels 30-33): Pelipper(50%), Gumshoos(30%), Slowpoke(20%)
Initial Pokemon - Nighttime (Levels 30-33): Pelipper(50%), Raticate(30%), Slowpoke(20%)
Surfing (Level 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
Fishing - Daytime (Levels 10-35): Magikarp(50%), Wishiwashi(40%), Clamperl(5%), Bruxish(5%)
Fishing SOS Pokemon #1 - Daytime (Levels 10-35): Gyarados, Wishiwashi, Gorebyss, Bruxish
Fishing SOS Pokemon #2 - Daytime (Levels 10-35): Gyarados, Wishiwashi, Clamperl, Bruxish
Fishing SOS Pokemon #3 - Daytime (Levels 10-35): Magikarp, Wishiwashi, Clamperl, Bruxish
Fishing - Nighttime (Levels 10-35): Magikarp(50%), Wishiwashi(40%), Clamperl(5%), Bruxish(5%)
Fishing SOS Pokemon #1 - Nighttime (Levels 10-35): Gyarados, Wishiwashi, Huntail, Bruxish
Fishing SOS Pokemon #2 - Nighttime (Levels 10-35): Gyarados, Wishiwashi, Clamperl, Bruxish
Fishing SOS Pokemon #3 - Nighttime (Levels 10-35): Magikarp, Wishiwashi, Clamperl, Bruxish
Fishing Bubble Spots - Daytime (Levels 10-40): Clamperl(35%), Bruxish(35%), Magikarp(20%), Wishiwashi(10%)
Bubble Spots SOS Pokemon #1 - Daytime (Levels 10-40): Gorebyss, Bruxish, Gyarados, Wishiwashi
Bubble Spots SOS Pokemon #2 - Daytime (Levels 10-40): Clamperl, Bruxish, Gyarados, Wishiwashi
Bubble Spots SOS Pokemon #3 - Daytime (Levels 10-40): Clamperl, Bruxish, Magikarp, Wishiwashi
Fishing Bubble Spots - Nighttime (Levels 10-40): Clamperl(35%), Bruxish(35%), Magikarp(20%), Wishiwashi(10%)
Bubble Spots SOS Pokemon #1 - Nighttime (Levels 10-40): Huntail, Bruxish, Gyarados, Wishiwashi
Bubble Spots SOS Pokemon #2 - Nighttime (Levels 10-40): Clamperl, Bruxish, Gyarados, Wishiwashi
Bubble Spots SOS Pokemon #3 - Nighttime (Levels 10-40): Clamperl, Bruxish, Magikarp, Wishiwashi
Trainers:
Ace Trainer Yuki - Level 34 Gible, Level 35 Marowak
Surfer Jennis - Level 36 Mantine
Swimmer Jared - Level 35 Tentacruel
Swimmer Jake - Level 35 Frillish
Swimmer Yumi - Level 35 Frillish
Swimmer Alexandria - Level 36 Bruxish
Swimmer Kyra - Level 35 Seaking, Level 35 Lumineon
Ace Trainer Karla - Level 36 Sandshrew, Level 36 Haunter, Level 37 Wigglytuff
Items:
Luxury Ball - From Lillie After Defeating Team Skull
TM62 - Near Surfing House
Dive Ball - Near Swimmers Jake & Yuki
Grip Claw - From Guzma After Defeating Necrozma