Part 1: Just started — no badges

Just started — no badges opens 6 areas. There are 14 trainers standing in them. The fights at this checkpoint are Rival Blue (Bulbasaur), Rival Blue (Charmander), Rival Blue (Squirtle), and 3 more.

Where to go

1. Viridian Forest

   Wild: Caterpie 40% · Lv 3-5, Weedle 40% · Lv 3-5, Kakuna 10% · Lv 4-6, Metapod 10% · Lv 4-6 +1 more

   Trainers: Bug Catcher Anthony Lv 8, Bug Catcher Charlie Lv 7, Bug Catcher Doug Lv 7, Bug Catcher Rick Lv 6, Bug Catcher Sammy Lv 9

2. Route 1

   Wild: Pidgey 50% · Lv 2-5, Rattata 50% · Lv 2-4

3. Route 2

   Wild: Pidgey 45% · Lv 2-5, Rattata 45% · Lv 2-5, Caterpie 5% · Lv 4-5, Weedle 5% · Lv 4-5 +1 more

   Pick up: HM05 Flash

4. Route 22

   Wild: Magikarp 100% · Lv 5, Psyduck 100% · Lv 20-40, Slowpoke 100% · Lv 20-40, Poliwag 60% · Lv 5-15 +6 more

   Trainers: ★ Rival Blue (Bulbasaur) Lv 9, ★ Rival Blue (Charmander) Lv 9, ★ Rival Blue (Squirtle) Lv 9, ★ Rival Blue — rematch (Bulbasaur) Lv 53, ★ Rival Blue — rematch (Charmander) Lv 53, ★ Rival Blue — rematch (Squirtle) Lv 53

5. Pallet Town

   Wild: Magikarp 100% · Lv 5-10, Tentacool 100% · Lv 5-40, Horsea 60% · Lv 5-15, Krabby 60% · Lv 5-15 +10 more

   Trainers: ★ Rival Blue (Bulbasaur) Lv 5, ★ Rival Blue (Charmander) Lv 5, ★ Rival Blue (Squirtle) Lv 5

6. Viridian City

   Wild: Magikarp 100% · Lv 5, Psyduck 100% · Lv 20-40, Slowpoke 100% · Lv 20-40, Poliwag 60% · Lv 5-15 +3 more

   Pick up: TM26 Earthquake

★ Rival Blue (Bulbasaur) — Pallet Town

1 Pokémon · level cap Lv 5 (every cap) · Rival Blue (Bulbasaur)’s own page

	Pokémon	Ability & item	Moves	Base stats
	Bulbasaur Lv 5 GrassPoison	Ability Overgrow	Tackle Growl	HP45Attack49Defense49Sp. Atk65Sp. Def65Speed45Total318

★ Rival Blue (Charmander) — Pallet Town

1 Pokémon · level cap Lv 5 (every cap) · Rival Blue (Charmander)’s own page

	Pokémon	Ability & item	Moves	Base stats
	Charmander Lv 5 Fire	Ability Blaze	Scratch Growl	HP39Attack52Defense43Sp. Atk60Sp. Def50Speed65Total309

★ Rival Blue (Squirtle) — Pallet Town

1 Pokémon · level cap Lv 5 (every cap) · Rival Blue (Squirtle)’s own page

	Pokémon	Ability & item	Moves	Base stats
	Squirtle Lv 5 Water	Ability Torrent	Tackle Tail Whip	HP44Attack48Defense65Sp. Atk50Sp. Def64Speed43Total314

Also fought around here

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.