- #1 is balance. If you see a row of four ships fly out from the left, it is likely that you'll see another row coming from the right (the only exceptions to this tend to be when spawns are dependent on the time of death of a prior enemy). You can easily see this as early as stages 1 and 2. In stage 2's second half, you can observe helicopters that spawn left, then spawn right for the entire last half of the stage.
- #2 is proximity. Proximity defines the speed of locking-on, which is important for speedy destruction of evildoers in stage 4. Proximity to enemies that are positioned near the top of the screen puts you in a place that makes it easy to misdirect bullets at a very sharp angle, allowing you to effectively manipulate enemy firing.
- #3 is that Kutswi has a variable rank mechanic, but it practically doesn't matter. Use P2 side for 13/14th of normal rank!
After this wave, there will be a wave that starts near the middle and spawns across the middle, then farther to the right. Immediately after, there will be spawns from middle to left. This entire half of the stage will require a bit of fiddling to make sure no popcorn traps you, and there's a vid up at the top of this post in case you want to see how the rest of the patterns play out. I am skipping to the first monster tank.
It's important to have the screen cleared by the time you get to the monster tank. There will be a column of tanks advancing on the big tank's position (thus, you) from the lower right side of the screen. It is important to be close to them or destroy some of them during the fight with the tank to ensure that no random snipes are thrown at you. Lock on quickly, move to the right. It works. It may not be necessary if you know that they're there beforehand and are ready to dodge. Skipping to the midboss.
The midboss can be pretty dangerous, but mostly only at the last pattern (assuming you shoot it nonstop from the beginning of the fight). For the spreads that are combined with long lines of red pointy things, moving to the lower left or right quadrant of the screen can give you a dodging advantage over staying directly under the midboss. The laser does decent damage, but it's OK if you move away to dodge. The dodging is more important than getting a little extra damage on the boss. As for the "last" pattern, I find that just moving quickly and not fearing the pattern makes it easier with practice. Get yourself into its rhythm and be prepared for it, then see the path and change your course as it comes.
Right after the midboss, there's a little patch of tanks and turrets. No problem, just be quick.
Immediately after these enemies, there will be a scattered wave of little helicopters that shoot dangerous blue stuff at you. Stay near the middle at the beginning, then go to the left side of the screen with your shot focused such that everything runs into it immediately, then time a sweep to the right such that you come out right under the nightmare (big red thing that cancels bullets when destroyed) and are able to lock-on and follow it to the left safely. The spread it fires is aimed directly at you, so if you're just under it and a little bit to the right of it, it will basically fire behind where you will be. If you stay up on it and have a lead, it will lead you and there's a decent chance of you dying. Once you can survive the initial entrance, there isn't much difficulty. Reference the movements of the player in the video if you need to see how to lead bullets away from you at some point.
Once this enemy dies, there are potentially two waves of spammy enemies, give or take, that spawn near the top/right of the screen (along with a bunch of tanks that are trivial to deal with at any point during this attack; they can usually even be ignored).
After the spammy waves, it is time to prepare for the first gigantic noobkiller of Cotsawee. The moving enemies that fire a fixed spinning blue thing and an aimed pink thing. The first three will spawn at the top right of the screen. Lockshot or pointblanking with shot will work just fine here. As the third one is about to die, getting to the bottom left corner of the screen is now paramount to your easy survival. The best way to handle this is to break the screen down into "things that are directly in front of your desired area of movement" and "things that are far away enough to ignore". The blue wave that is closest to you will be the first thing you want to concentrate on moving quickly through. It is rather simple, but they can overlap if you leave enough alive and don't get to the bottom-left early enough. The advantages of that corner are numerous, and learning this section will be particularly satisfying to anyone who used to think it was unpopsicle. I now skip to the part immediately after.
Immediately after this section, there will be a wave of blue-spamming zako from the left side of the screen. Wait for them, kill them, and be prepared to quickly lock onto or shot-kill another loopy enemy that spawns on the upper left side of the screen. There will be some more popcorn and stuff, but the biggest part of this battle is being ready for the initial popcorn wave.
There is another monster tank on the upper right side just after this. This one fires a lot more frequently and is far more dangerous, but moving from a position lined up with the left edge of the tank (though nearer to the bottom of the screen) in a clockwise-ish motion should keep you safe from the deadly spams. If you come up with your own method, it'll probably be more comfortable for you.
The entire rest of the stage (not including the boss) is basically a test of how well you've learned the earlier parts of the stage. I'll leave it to you to pass this test unscathed.