I think it is Lucha? He wasn’t even in my dreamies list, I was thinking about moving him out even but he eventually grew on me and became one of them. 3 years and counting
For me, it's Hugh and Mint. They were both starters in Sakura that I decided to make permanent residents, so they have been with me since October 2017 and I expect them to be in my town forever.
Poppy moved into my first New Leaf town in November 2013, and is still in my town to this day. Even if you don't count the years I wasn't playing in that town (I stopped around November 2015), that's probably still the longest time I've ever had a villager.
The main reason why I've had her for so long is because she's my absolute favourite villager along with Melba - if she asked me about moving, I would be like 'No. You're staying here forever and ever.' Lol
I restarted my New Leaf town in January 2017 for a challenge here, but Lucky was one of my starting villagers and is still living it up 3+ years later.
My memory isn't that good, but I think my starters in New Leaf back in 2013 were Kiki, Pate, Lyman and Anchovy? Only one of those villagers moved out. I miss Pate so much still.
Stinky. I've been playing since December of 2019 and he hasn't even asked to move out yet. That's pretty good to me, because he's my favorite villager.
I've been playing my town since 2015 and I think I've had Kid Cat, Freckles, and Static since the beginning. I was never very serious about playing, and I didn't really put together a list of dreamies until recently, so they've just been hanging around for years and years. I finally had Static move out only last week! Sad to say but I was glad to see him leave...his house is bright pink with a tin door and barbed wire fencing, just terrible XD I wouldn't say no if Freckles or Kid Cat asked to leave either at this point.