The ghost type Pokemon is viewed as highly common. Many of them move and have low HP. This ghost-type is useful in battles as this is the only kind, which has two immunities: fighting and normal and both of them are common types of move. From the 6th generation, the ghost-types Pokemonbecome immune to abilities and moves, which prevent escaping just like Shadow Tag and Block. These Pokemons are generally connected to the dark, fear, and afterlife. They live usually in cemeteries, abandoned houses, uninhabited dark places, and funeral places. The ghost Pokemon are known to be very naughty and pranking and humans can just see their faces.
Relation with the other kinds
The ghost-type Pokemonsare very strong against psychic types as some people are very afraid of ghosts and fears of ghosts affect the mind. Communicating with ghosts is a different process rather than reading minds through empirical and physical means.
They are very strong against themselves as ghosts can touch one another and only the strongest spirit wins. Spirit is the desire to win. They are weak against dark types as dark signifies evil and terror and the evils are punished. It is believed that ghosts who have evil lives and do not go to the afterlife get transformed into demons. Demons are feared in some mythologies and they are said to eat souls that are lost.
They are immune to the normal and fighting types as spirits are incorporeal and they cannot hit in a usual way. A ghost and a mortal cannot hurt one another. The fighting kind is not immune. The poison type is resisted because you cannot poison a person who is already dead. As spirits do not possess a physical form, toxins cannot pass.
The bug-type is resisted as the members of this kind cannot transcend easily to the members of the spiritual barrier and the parasites cannot infect a person who is dead already.
Haunter, Gastly, and Genger
Haunter, Gastly, and Genger are the ghost-type Pokemon. Gengar and its family became very popular in the first generation provided that the original Blue/Red/Yellow had mistakes and this made psychic kinds immune to ghost-kinds of the move though they should have been highly effective. This was subsequently corrected in the next generations.
Haunter evolves to Gengar through trade; however, you can catch wild Gengar in Pearl, Diamond, and Platinum. They appear in Old Chateau in case there is a third-generation game. You can read more about Pokemonghosts online.