I know you can find water Pokémon near water, and grass Pokémon near... well grass. But what about Ghost/Poison/Psychic (let's just say "GPP" for short) type Pokémon?
I heard a rumor that you can find GPP Pokémon at night, but the only GPP Pokémon I've caught have just been in random suburb areas during the daytime, along with grass type Pokémon. Is there a specific location where you can find GPP type Pokémon? Or are they just rare and randomly placed?
I think you will find this link helpful: http://www.pokemongodb.net/2016/04/pokemon-go-types.html
It has a chart at the top showing what percentage of Kanto pokemon belong in each type. Below, it shows a list of all Pokemon in the game and after that there is a chart showing what type of Pokemon to expect in various Biomes.
Happy Hunting!
Normal
Boundaries, Landuse, Places, Roads, Transit, College, Commercial, Common, Footway, Hospital, Hotel, Library, Major Road, Minor Road, Pedestrian, Pitch, Playa, Recreation Area, Retail, Runway, School, Sports Center, Stadium, University
Grass
Landmass, Farm, Farmland, Farmyard, Forest, Garden, Golf Course, Grass, Meadow, Nature Reserve, Park, Path, Playground, Residential, Wood
Bug
Farm, Farmland, Farmyard, Forest, Garden, Golf Course, Grass, Nature Reserve, Park, Path, Playground, Wood
Water
Water, Basin, Canal, Dock, Drain, Glacier, Lake, Ocean, Reservoir, River, Riverbank, Stream
Flying
Farm, Farmland, Farmyard, Forest, Garden, Grass, Nature Reserve, Park, Wood
Rock
Building, Landmass, Highway, Industrial, Parking, Quarry, Railway, Urban Area
Ground
Landmass, Ditch, Land, Parking, Playground, Railway, Taxiway, Urban Area
Fairy
POIs, Cemetery, Place of Worship
Dark
Cemetery, Cinema, Theatre
Steel
Building, Railway
Dragon
POIs
Ghost
Cemetery
Ice
Glacier
Psychic
Hospital?
Electric
Industrial
Fire
Residential?
Poison
Wetland
Are there any other ghost types in Gen 1 besides the Gastly family? Anyways, I've found a few in urban locations and a few in suburbs. I have also heard that they are more common at night. I can't say for sure because I've largely been hunting in the evenings so my 'data' would be biased.
The only current ghost type Pokémon are from generation 1 (the Gastly family - Gastly, Haunter, and Gengar). These can be caught at any time of day, although they are more likely to appear at night. I am not aware of any location restrictions for Ghost-type Pokémon at this time. Thanks to user Ellesedil for pointing this out with evidence of daytime appearance here.
Furthermore, there is no hard evidence that Gastlys (or other Pokémon) appear more often at night. Several sources (such as Polygon's guide) claim that Gastly spawns more frequently at night, but don't offer any source or evidence, so take this how you will. Personally I have seen two Gastlys at night and two during the early afternoon, so it is entirely possible that any night time relation is false.
Edit: After the edit to the question, my response is that there is no such delineation as "Purple Type" and that Psychic and Ghost are different types and have different spawning/location-time rules.
For Poison:
I've know 2 locations at my town that have a ton of Nidoran spawns.
Zubat apparently spawns everywhere, day or night.
For Psychic:
I know 1 location which spawns a lot of Abras, another location that spawns a lot of Drowzees. Also caught a random Jynx at one point. Drowzee is more an urban area while Abra is more grassland.
For Ghost:
I cannot say for sure, I've seen Ghastly in all places I went to, its just super rare. Also I've noticed that Ghastly shows up around 2x-3x at night.
