From Bulbapedia, the community-driven Pokémon encyclopedia.
The Pokémon Tower is the buiral site for all the Pokémon in Kanto. It houses the graves of countless Pokémon. Many people visit it daily to pay their respects to the fallen. It is located in Lavender Town.
Aside from graves, it also houses wild Cubone as well as many Ghost-type Pokémon. In Generation I,Team Rocket tried to steal the Cubone so they could sell off their valuable skulls. In the process, a mother Marowak was killed. Mr. Fuji tried to confront the criminals but ended up being taken hostage.
The ghost of the mother Marowak haunted the tower till the main character is able to knock it out and dispel it. The Marowak that appears here cannot be caught, even if a Master Ball is used.
The Ghost-type Pokémon in the tower appear to have a unique ability to disguise themselves as the ghosts of humans. However, a Silph Scope will reveal their true natures.
The tower is seven stories tall. Wild Pokémon do not appear on the first floor.
Some items found in the tower in Generation I include an Escape Rope, an Awakening, an Elixir, an HP Up, a Nugget, an X Accuracy, and a Rare Candy.
In Generation II, the tower is converted into a Radio Tower, broadcasting music and radio programs to the radios and PokéGear of Kanto. The graves are relocated to a building south of the tower.
Pokémon that Appear in Pokémon Tower