Ranked battles in SwSh have a bunch of little rules regarding what Pokemon and things are allowed, and they change every so often. You can see a list of rules for each season here:
https://serebii.net/swordshield/rankedbattle.shtml (click on the one that is for the current time period/season)
If I had to hazard a guess as to why Incineroar and Primarina are not allowed, you probably transferred them from the last generation, and most Pokemon not born in Galar are not allowed to be used in ranked battles until they have some thing done to them at the Battle Tower.