Part 5: Beat Norman — Petalburg City Gym, badge 5

Beat Norman — Petalburg City Gym, badge 5 opens 3 areas.

Where to go

1. Southern Island

   Wild: Latias Lv 30, Latios Lv 30

2. Route 119

   Wild: Oddish 100% · Lv 12, Castform Lv 30, Kecleon Lv 30

3. Route 118

   Wild: Electrike 60% · Lv 12, Wingull 35% · Lv 12, Kecleon 5% · Lv 12

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

It also doesn't say when 9 of its areas open up, so they are listed together in the last part rather than guessed into the story.