Since I have a lot written down for these two villainous factions, let's get into how I developed them!
INSPIRATION
Because I picked the Hoenn region for the setting, it's more than appropriate that I'd include one of my favorite elements of the region; having two teams at war! It also allows me to use more villagers through the story, since one of my plans was always to include every single villager in some capacity.
The names Cottage and Pastel, unsurprisingly, come from online aesthetic movements. With the Animal Crossing series, making an aesthetically pleasing town/island became a bigger priority in the "New" games (that being New Leaf and New Horizons, respectively). This is due to more customization options. While New Leaf was the first game I played, I was one of the players that focused more on hanging out with my villagers than decorating my house or town to look absolutely perfect. Once New Horizons came around, I definitely ended up focusing on decoration/renovation, while I'd end up not doing much with my villagers.
The parts about personally picking new recruits rather than letting anyone join? That part's a reference to the Animal Crossing amiibo cards, where the player can pick any villagers they want (want a pink all-normal island? all cats or bunnies or deer? Bring it on!) rather than like the older games, where villager choices are random (this ties into my boys too, since Benedict, Kidd and Tank were all villagers I had randomly in my first New Leaf town, and I got attached to those little guys!)
VILLAGER SPECIES AT PLAY
I picked Dobie and Judy as the leaders since both villagers fit their respective aesthetics (Dobie and his woodsy forest look, Judy and her flashy colorful 'kawaii' appeal), their species coming into play (the most aggressive bears are mothers whose cubs are in danger, and Judy sees herself as a maternal figure to her underlings, like Mom from Futurama) (the whole dynamic with wolves as predators and the "alpha wolf" archetype), and villager personalities seen as antagonistic (the snarky aloof cranky, the uppity gossipy nature of snooties) and mesh against each other. I also happen to ship Maxie/Archie in a mutually toxic dynamic, so Judy and Dobie would end up as exes at war.
As for the admins... Beau and Fauna were both picked because deer are prominent in the cottagecore movement, and are typically seen as cutesy harmless animals despite bucks fighting with their antlers over does. I had considered rabbits joining Cottage, but the Killer Rabbit angle is more fun to explore with deer than rabbits. As for why they're both deer? Let's just say that species plays a big part in Dobie's vision (exploring the darker aspects of cottagecore adopted by....unsavory people)
Julian and Filbert were picked since their pastel blue colors complement Judy's pink color scheme. Species isn't as important to Judy, and I picked two villagers I happened to like. Julian himself is primarily based on Dorian Red Gloria (the protagonist of From Eroica with Love), due to his pretty looks, ruthlessness, and obsession with someone who isn't romantically interested back. Filbert is an "only sane man" whose more level-headed compared to the exaggerated camp. Pastels as an aesthetic can be needlessly toxic, which is why everyone wears purple!
I also picked villagers that happened to be fairly popular, since good antagonists should be compelling enough rather than something for the obstacle to stomp down. This is why Judy's friendship with Julian and Filbert is genuine, even beyond their roles as ecoterrorists. Also, Judy as one of the new faces of New Horizons is why I picked her in particular for a team leader rather than an older villager like, say, Marina or Rosie.
There are several lines tossed around about the major trio not being Pastel or Cottage material. This is because of their status as "plain" villagers (not infamously ugly, not excessively cute, kinda just there), so no chance of them betraying each other any time soon