Can I find a lot of really good and rare Pokémon in a rural area without incense? I want a Gyarados, but I am about two miles away from water.
Yes, it's possible to find rare Pokémon anywhere, as spawns are random. Incense may increase spawn rate for you, but from my personal experience, I've never had any incense spawns uncharacteristic of the surrounding area.
The likelihood of encountering a rare Pokémon may be lower if you're in a rural area, however, but that doesn't make it impossible.