Go to this link, there is an article that explains where you can find the different types of Pokemon:
Just in case you can't access it, for some reason, here's the list:
Normal - More or less everywhere - that's why they're called Normal
Fire - Residential areas and neighbourhoods, warmer areas like beaches
Water - Rivers, streams, lakes, harbours, beaches - anywhere where there's water
Grass - Farms, forests, and parks are good options, as are gardens and golf courses
Bug - Farmland, woods and forests, gardens and generally grassy areas like parks, nature reserves, smaller pathways, golf courses and playgrounds.
Rock - Quarries, towns, parking buildings, train stations, highways, or large buildings such as shopping malls
Ground - Ditches, streams, parking garages, playgrounds, railway stations, roads and generally urban areas.
Electric - Industrial parks, schools and college campuses, and other dry places that are largely concreted over
Fighting - Sports centres and stadiums, and they’ll also congregate around larger gyms.
Poison - Ponds, marshes, lakes, more industrial areas of cities and in large buildings
Fairy - Places of interest (local landmarks), churches or the cemetery.
Flying - Farmland, forests, woods and grassy areas such as nature reserves, playgrounds, parks and gardens.
Dragon - Famous places or landmarks
Ghost - Occasionally around churches, but they’ve also been reported to show up in built-up residential areas such as parking lots at night.
Ice - Grassy areas occasionally and near bodies of water more often than that. You’ll of course also find them anywhere there’s actual snow and ice.
Psychic - Grassy areas, but that’s pretty uncommon in general. Some also show up in residential areas but seemingly only at night. A better place to more reliably find them is in and around hospitals.
Steel - Inside or around larger building structures. They can also be found near railway stations and tracks.
Dark - In cinemas and theatres.