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Patchouli is one of those catch stages, where you can pick between marisa A or B and Reimu A or B and you will encounter different spells.

I always use marisa B because that is the easiest for me. There is only one spell I have to master spark through. For her its best to be on guard, and improvise each time if your changing characters, otherwise stay with the same character setting and keep practicing.

Sakuya, can be a little difficult, since some of her spells bounce off walls. Well most of them do.
Her trickiest spell is misdirection, even on normal you can die easily. That will be your first encounter with her. For her you want to actually listen very closely at her spell cues and her time freezes so you can keep a grip on where the time will slow down. Make a plan when the time freezes and always go where less knives in the direction. Her last spell can be misdirected.

Slight movements, destroy the books as soon as they appear.

As for Sakuya, don't panic, the knifes are relatively slow compared to most projectiles.

For stage 5:

The initial waves of fairies come in two types - pair of fairies that shoot aimed bullets at you, and a bunch of ones that scatter them around. If you aren't confident with dodging the scattered bullets, bomb. You can also trivialize the part by standing on the upper side of the screen at correct places, but you'll have to look at a replay for that.

Afterwards comes some more fairies that shoot aimed bullets. Tiny dodge after the first two pairs, then tiny dodge again after the third pair finishes shooting. Try to end up in the center afterwards.

The next four fairies shoot a whole bunch of walls around that like to trap you. Kill them ASAP or just bomb.

Midboss Sakuya's non-spell is all about trapping you. You have three ways to deal with it - 1) learn the pattern so you know where to move; 2) move in between the red kunais (there ARE space for you to fit through, though it's probably hard to do without the hitbox patch), or 3) go above her, but close enough to her that you can still hurt her (you can skip all the bullets this way, but Sakuya might make a random movement and ram you)

Misdirection on easy/normal is easy - everything is aimeed. The trick is how to hurt Sakuya if you aren't using ReimuA. The best way is to stand on one of the sides and just swing back and forth. On Hard/normal the red kunais will bounce so you'll have to deal with them, but otherwise it's the same strategy.

The fairies afterwards shoot lots of flak that are mostly aimed away from you. Don't move unless you have to and you'll be surprised how easy it is to dodge them. Near the end of the stage you get more aimed bullet shooting fairies - stream them.

Boss Sakuya time:
For non-spell #1, don't hug the bottom or you'll easily get trapped. Otherwise it's more or less dodge or bomb.
Spell #1: It's hard on normal but pretty easy on hard/lunatic, as weird as it may seem. The idea is to use the time stop to figure out a route through the flak of fireballs (easy/normal) or bubbles (hard/lunatic), and then weave to the side a bit. On Easy/Normal you have to deal with some knives too, but on Hard/Normal you don't have to. The other important thing is to always line up with Sakuya when you're done dodging a wave, or next wave is going to be diagonal and harder to dodge.
For nonspell#2, again, don't hug the bottom. This is a really hard attack on Hard/Lunatic, but not that hard below.
Spell #2: When Sakuya fires the bullets/fireballs, immediately swing to her sides so all the knives that appear will be directed mostly away from the space below her, then swing back below her when the knives are done appearing and redirecting.
Nonspell #3: Not much I can say about this one, either, other than (again) stay off the bottom.
Spell #3: Bomb. Both Marionette and Killing Doll are annoyingly hard and there are not much pattern. Marionette also has a nasty tendency to backshoot you (killing doll does it waay less often), so you don't really want to risk your lives for that one.