Don't know if this has been posted yet. Someone made this entire map of every Pokémon on every route. If you don't want to spoil the game for yourself I recommend not looking until you've beaten the elite 4.
That map is awesome but i've noticed some things that might be wrong: - I have pokemon Y and found a weedle in santalune forest - I don't know if this is something that's wrong, but i've only seen dugtrio on route 13. No diglett's - I can't for the life of me find ekans/arbok on either route in pokemon Y, probably just my AWFUL luck - You can also find single scythers in route 21