Part 2: Beat Cilan, Chili or Cress — Striaton City Gym, badge 1

Beat Cilan, Chili or Cress — Striaton City Gym, badge 1 opens 3 areas.

Where to go

1. Route 3

   Wild: Audino 100% · Lv 8-11, Basculin 100% · Lv 5-15, Goldeen 60% · Lv 35-55, Pidove 40% · Lv 8-11 +5 more

2. Wellspring Cave

   Wild: Basculin 100% · Lv 5-15, Drilbur 100% · Lv 10-13, Poliwhirl 55% · Lv 35-60, Roggenrola 50% · Lv 10-13 +3 more

3. Nacrene City

   Wild: Aerodactyl Lv 25, Anorith Lv 25, Archen Lv 25, Cranidos Lv 25 +5 more

Everything you can have caught by this checkpoint · Open the interactive guide

It also doesn't say when 4 of its areas open up, so they are listed together in the last part rather than guessed into the story.