FCorrin has been performing even better than expected in PVP. She does beat all Falchion users and red dragons one-on-one in a vacuum although she does take a beating, but her most important asset is definitely her shadow breath. If you can nail the whole enemy team with it, which isn't really difficult, the debuff is so crippling that with a bit of care with your positioning you can generally just rush in and jump the enemy team with the rest of your characters and expect to go 4-0.
I wonder if an optimal team to make full use of her might not have a few mounted and flying heavy hitters to best flank the enemy team once they get Shadow Breathed, with preferably at least one but maybe even two of them being tome users to take full advantage of her Seal Resist. Interesting, Corrin/Camilla/Leo/Elise seems like it might be a really fucking good team...
In case anyone's figured it out, how do tiers work? My tier has been going up just from chaining Beginner difficulty players, and I'm not sure why.
My understanding is that each season your rank is determined by your score relative to everyone else at that point in time. So it should constantly fluctuate as everyone else's and your scores change (it might be calculated at certain intervals or it might be real time, I don't know). Keep in mind that early in the season most players won't have gotten their full seven-win streak yet, so until the third full day at least it'll be very volatile.
Do you have any of the featured characters? Since very few people seem to this time around having even one on your team should massively inflate your score. I'm working on raising up Narcian now hoping the rest of my team can carry him through seven wins, but if you have one of the new 5*s you'll be at a huge advantage.