Interesting observation, there is one pair that has its own territory and another trio- there are two females and one is dominant towards the other but they stay near each other and near the same male.
They used to fight viciously, and traded places as the partner of the same male, to the point one of them has slight jaw damage from the violence.
Now they are not completely peaceful but they don’t try and chase each other out of their territory, one is aggressive towards the weaker one but it remains near it in the same territory unlike the past when the weaker one had to hide.
And there has been no breeding of any of these fish, maybe there is too much crowding and aggression.
Every youtube video seems to show a pair of vaillantis in a community tank, maybe this is a good way to keep them since I saw a pair turn into a male bullying a female when I removed the other fish in the tank.