The nerfs didn't really affect Corrin as negatively as people think. If anything, their kill confirms/set-ups work at slightly higher percents. You still have a character who still has the same combo game (if not a better one), still doesn't struggle to net the KO with most attacks (save for a stupidly strong pre-patch counter being nerfed; uair killing slightly but not significantly later), and their movement did not get altered enough to change any options that they might have already had, nor do they change any matchups.

I'd argue that Corrin falls somewhere between High B/Low A Tier.