Wow yeah that's a great Pokedex. I'm still missing a bunch of the standard Pokemon, like Machamp, Machoke, and Kadabra. I don't even have a Dragonite. D; I do have the legendary birds, Lugia, and Raikou. I missed Suicune and Entei though. :S
As for Unown, it's the rarest non-raid, non-region locked Pokemon with active spawns. You either have to get extremely lucky, or you go to special events where Unown are released with less rare spawn rates. I have E, U, R, O, and P. You can guess what that event was all about. They didn't spawn all across the continent, though, only in some very specific cities and areas. I was lucky enough to live only an hour's drive away from one of the locations. Unown have also been released in Chicago and Japan with increased spawns. It was still pretty tough getting all of the letters that were available. My boyfriend drove me around for a long time. Couldn't have done it on foot. We only had the one day to be there.
Delibird and Smeargle haven't been released yet. Smeargle might have an issue with its moveset which needs to be sorted out first, and they're probably waiting to release Delibird for Christmas. That's my guess at least.
Hopefully, in the future, Niantic will introduce ways to get legendaries that are friendlier to rural players and even urban players who live in towns and cities that just don't have enough activity for raids. You have to be lucky with where you live to be able to get legendaries at the moment, which doesn't seem fair. I do think you should have to work for them and not just randomly run into one like any other rare Pokemon, but I'm sure there's a solution for that.