Wait, what? Rank in PCB? I haven't noticed anything like that.
What I've generally seen in regards to this is that rank does exist in PCB, but unlike EoSD, it's so subtle that it's basically a meaningless number and something you can ignore 99% of the time. The only PCB attack I've seen anyone mention rank on is, as Donut mentioned, Lyrica's opener, which
Kefit also mentions here.
Of course, as a Reimu player, I end up fighting Lunasa, and I've never encountered this attack outside of the two Marisa 1ccs I've done, so I don't actually have any experience of my own to draw conclusions from. For all I know, this thing called "max rank" is just a bad case of nervousness.
On a slightly related note, is there a general opinion on the difficulty of each Prismriver's individual spellcards and non-spells? I've only really ever bothered with Lunasa (Reimu) and her "thing" seems to be claustrophobia and really small dodging space. I've gotten used to that by now but when I've tried other sisters they completely obliterate me. Any opinions on them?
For Normal, you're probably fine sticking with Lunasa. Lunatics tend to go for Lyrica due to her tap-stream noncard and relatively easy spellcard,
but something about that spellcard seems to be more difficult on Normal than it is on Lunatic I typed that out, then decided to go back and test it for myself. It doesn't just "seem" more difficult. That is
NOT a Normal difficulty spellcard. It's definitely more difficult than its Lunatic equivalent.
Don't fight Lyrica on Normal.I don't have much experience with Merlin, but I seem to recall curvy lasers on that front. I'd reject it just based on that.