Part 13: Got the Rainbow Pass — Four to Seven Island
Celio asks for the Ruby once you have the National Pokédex, which Professor Oak hands out after you beat the game. In return you get the Rainbow Pass, which opens Four through Seven Island. Delivering the Sapphire the same way clears the guard blocking Cerulean Cave.
Got the Rainbow Pass — Four to Seven Island opens 26 areas. There are 71 trainers standing in them.
Where to go
Monean Chamber
Wild: Unown 100% · Lv 25
Liptoo Chamber
Wild: Unown 100% · Lv 25
Weepth Chamber
Wild: Unown 100% · Lv 25
Dilford Chamber
Wild: Unown 100% · Lv 25
Scufib Chamber
Wild: Unown 100% · Lv 25
Rixy Chamber
Wild: Unown 100% · Lv 25
Viapos Chamber
Wild: Unown 100% · Lv 25
Cerulean Cave
Wild: Magikarp 100% · Lv 5, Geodude 65% · Lv 30-50, Psyduck 65% · Lv 30-50, Slowpoke 65% · Lv 30-50 +17 more
Icefall Cave
Wild: Magikarp 100% · Lv 5, Tentacool 95% · Lv 5-45, Horsea 80% · Lv 5-15, Krabby 80% · Lv 5-15 +21 more
Trainers: Team Rocket Grunt Lv 38
Pattern Bush
Wild: Ledyba 30% · Lv 9-14, Spinarak 30% · Lv 9-14, Heracross 20% · Lv 15-30, Kakuna 20% · Lv 9 +3 more
Trainers: Bug Catcher Garret Lv 49, Bug Catcher Jonah Lv 47, Bug Catcher Vance Lv 48, Camper Riley Lv 50, Lass Dalia Lv 48, Lass Joana Lv 49 +6 more
Lost Cave
Wild: Haunter 30% · Lv 44-52, Gastly 25% · Lv 38-40, Golbat 20% · Lv 41-43, Misdreavus 20% · Lv 15-22 +2 more
Trainers: Lady Selphy Lv 49, Psychic Laura Lv 49, Ruin Maniac Lawson Lv 49
Resort Gorgeous
Wild: Magikarp 100% · Lv 5, Horsea 80% · Lv 5-15, Krabby 80% · Lv 5-15, Tentacool 65% · Lv 5-40 +9 more
Trainers: Lady Gillian Lv 49, Lady Jacki Lv 50, Painter Celina Lv 50, Painter Daisy Lv 50, Painter Rayna Lv 50, Swimmer♂ Toby Lv 48 +1 more
Water Labyrinth
Wild: Magikarp 100% · Lv 5, Horsea 80% · Lv 5-15, Krabby 80% · Lv 5-15, Tentacool 65% · Lv 5-40 +10 more
Trainers: Pokémon Breeder Alize Lv 48
Five Isle Meadow
Wild: Magikarp 100% · Lv 5, Horsea 80% · Lv 5-15, Krabby 80% · Lv 5-15, Tentacool 65% · Lv 5-40 +14 more
Trainers: Team Rocket Grunt Lv 48, Team Rocket Grunt Lv 49, Team Rocket Grunt Lv 48
Memorial Pillar
Wild: Hoppip 100% · Lv 6-16, Magikarp 100% · Lv 5, Horsea 80% · Lv 5-15, Krabby 80% · Lv 5-15 +9 more
Trainers: Bird Keeper Chaz Lv 49, Bird Keeper Harold Lv 49, Bird Keeper Milo Lv 49
Pick up: TM42 Facade
Outcast Island
Wild: Magikarp 100% · Lv 5, Tentacool 95% · Lv 5-40, Horsea 80% · Lv 5-15, Krabby 80% · Lv 5-15 +8 more
Trainers: Fisherman Tylor Lv 49, Sis And Bro Ava & Geb Lv 50, Swimmer♀ Nicole Lv 50, Swimmer♂ Mymo Lv 49, Team Rocket Grunt Lv 48
Green Path
Wild: Magikarp 100% · Lv 5, Tentacool 95% · Lv 5-40, Horsea 80% · Lv 5-15, Krabby 80% · Lv 5-15 +8 more
Trainers: Psychic Jaclyn Lv 49
Water Path
Wild: Magikarp 100% · Lv 5, Tentacool 95% · Lv 5-40, Horsea 80% · Lv 5-15, Krabby 80% · Lv 5-15 +17 more
Trainers: Aroma Lady Rose Lv 49, Hiker Earl Lv 49, Juggler Edward Lv 48, Swimmer♀ Denise Lv 49, Swimmer♂ Samir Lv 50, Twins Miu & Mia Lv 50
Ruin Valley
Wild: Magikarp 100% · Lv 5, Marill 100% · Lv 5-25, Wooper 100% · Lv 5-25, Poliwag 60% · Lv 5-15 +12 more
Trainers: Hiker Daryl Lv 50, Pokémaniac Hector Lv 49, Ruin Maniac Foster Lv 50, Ruin Maniac Larry Lv 49, Ruin Maniac Stanly Lv 48
Trainer Tower
Wild: Magikarp 100% · Lv 5, Tentacool 95% · Lv 5-40, Horsea 80% · Lv 5-15, Krabby 80% · Lv 5-15 +9 more
Trainers: Psychic Dario Lv 52, Psychic Rodette Lv 50
Canyon Entrance
Wild: Sentret 30% · Lv 10-15, Spearow 20% · Lv 44, Fearow 15% · Lv 48-50, Phanpy 15% · Lv 10-15 +4 more
Trainers: Aroma Lady Miah Lv 50, Juggler Mason Lv 47, Pokémon Ranger Madeline Lv 51, Pokémon Ranger Nicolas Lv 51, Young Couple Eve & Jon Lv 50
Sevault Canyon
Wild: Geodude 65% · Lv 25-40, Graveler 35% · Lv 30-50, Phanpy 20% · Lv 15, Fearow 15% · Lv 50 +7 more
Trainers: Cool Couple Lex & Nya Lv 52, Cooltrainer Leroy Lv 50, Cooltrainer Michelle Lv 50, Crush Girl Cyndy Lv 48, Pokémon Ranger Jackson Lv 49, Pokémon Ranger Katelyn Lv 52 +1 more
Tanoby Ruins
Wild: Magikarp 100% · Lv 5, Tentacool 95% · Lv 5-40, Horsea 80% · Lv 5-15, Krabby 80% · Lv 5-15 +9 more
Trainers: Gentleman Clifford Lv 49, Painter Edna Lv 50, Ruin Maniac Benjamin Lv 48, Ruin Maniac Brandon Lv 50
Four Island
Wild: Magikarp 100% · Lv 5, Marill 70% · Lv 5-25, Wooper 70% · Lv 5-25, Poliwag 60% · Lv 5-15 +5 more
Also open from here
2 more areas the same checkpoint opens, each with its own page.
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.