I'm for Roselia as Low-A (at least). Natural Cure,a good resistance on super-effective attacks and special defense awarded to it by eviolite it, does really an essential part for any good stall team, since it's also the best spiker, more than Scopelide and Garbodor. I think it's able to put more layers than the other two.
I have to agree with Quasar. I've used Rosy a couple of times on my teams and I just see him as working so well alongside Alomomola. Besides that, he gets free switch-ins on lots of neutrally effective attacks, and can set up the Spikes that she's famous for while forcing something like Seismitoad or Golem to switch out. She may not be as useful as another Spikes setter such as Scolipede overall but at being a defensive user of the move as well as a status absorber on a team with no Heal Bell (like mine) I think she is outclassed by none in the tier.