Walkthrough
Since the Cinnabar Island Gym will be locked when you arrive on the island, you will need to go searching for the key to the Gym within the nearby Pokemon Mansion. This building is full of both Wild Pokemon and Trainers, and was where the Pokemon known as Mewtwo was once stored. You will need to use the switches on the statues found throughout the structure to access certain areas within it.
Wild Pokemon
First/Second/Third Floor:
Koffing (40%): Levels 39-44
Rattata (20%): Levels 39-44
Raticate (20%): Levels 39-44
Magmar (14%): Levels 39-44
Weezing (5%): Levels 39-44
Ditto (1%): Levels 39-44
First/Second/Third Floor - Special Spawns:
Chansey: Levels 39-42
Basement Floor 1:
Koffing (30%): Levels 39-44
Rattata (20%): Levels 39-44
Raticate (20%): Levels 39-44
Magmar (10%): Levels 39-44
Weezing (10%): Levels 39-44
Ditto (10%): Levels 39-44
Basement Floor 1 - Special Spawns:
Chansey: Levels 39-42
Trainers
First Floor:
Scientist Ted: Level 45 Electrode, Level 45 Muk
Second Floor:
Burglar Arnie: Level 44
Coach Trainer Rita: Level 46 Graveler, Level 46 Dugtrio, Level 47 Poliwhirl
Ace Trainer Louis: Level 45 Kingler, Level 46 Primeape
Third Floor:
Scientist Braydon: Level 45 Weezing, Level 45 Magneton, Level 45 Magmar
Burglar Simon: Level 44 Magmar, Level 44 Muk
Basement Floor 1:
Burglar Lewis: Level 44 Koffing, Level 44 Koffing, Level 44 Koffing, Level 44 Weezing
Scientist Ivan: Level 45 Electabuzz
Obtainable Items
First Floor:
Silver Razz Berries: Near Stair Down From Third Floor
Fire Stone: Near Scientist Ted
Max Repel: Northwest Room
Max Elixir: Middle Room
Max Lure: Under Eastern Table
Second Floor:
Poke Balls: Defeat Burglar Arnie
Max Ether: Near Burglar Arnie
Ultra Balls: Near Southeast Hole
PP Up: Southwest Room
Max Revive: Northeast Room
TM22: Defeat Coach Trainer Rita
Ultra Balls: Defeat Ace Trainer Louis
Hyper Potion: Near Ace Trainer Louis
Third Floor:
TM21: Northeast Room
Full Heal: Behind Northern Statue
X Accuracy: Near Scientist Braydon
Poke Balls: Defeat Burglar Simon
Rare Candy: Near Burglar Simon
Basement Floor 1:
TM52: Southern Middle Room
Max Potion: Far Southwest Corner
Poke Balls: Defeat Burglar Lewis
Rare Candy: Northern Middle Room
Max Elixir: Near Northwest Cloning Machine
Secret Key: Room South Of Cloning Machine
Post Game
Walkthrough
After defeating the Elite Four and starting the Master Trainers Challenge, you will find a few Master Trainers in the Pokemon Mansion. In total, there will be two Master Trainers to defeat.
Trainers
First Floor:
Ace Trainer Jace (Master Trainer): Level 75 Magmar
Second Floor:
Scientist Gordon (Master Trainer): Level 75 Muk