I was just rereading the "Rank System in Basic" section in light of Trap's findings, and I have a few suggestions for things that could stand to be updated to reflect our current understanding. (There are also a couple things that are left over from the Garegga guide that I'll note, too.)
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"Play for score": this section still features a mention of the fixed stage 3 extend in Garegga.
"Don't hoard bombs": likewise, this references the Garegga flamingoes.
"Don't hoard lives": not an inaccuracy, per se, but it might be worth adding that it's even more important to avoid hoarding lives not just to maximize your rank decrease upon death, but also because extend items generate a HUGE amount of rank, and that amount is increased heavily when you have more lives in stock.
"Use large items to power up when possible": if Trap's rank information is correct, the opposite should be true: small shot powerups give only 256 rank, while large ones give 32768(!). Weapon fragments are a similar (but less severe) story: small weapon fragments give 2048, while large weapons give 131072, with no additional rank for completing a full weapon. (40 small weapon fragments = 81920, or less than 2/3 the rank of a large weapon item).
"Be wary of raising the autofire rate": on the contrary, it seems like this can actually be preferable compared to picking up a bunch of options, at least for the purposes of rank control. There's no per-frame rank increase, so the only thing that changes is the extra rank generated from firing more shots. Plus, it can obviously be lowered at will.
"Don't collect power-ups when your power is 'maxed'": there's no (extra) rank increase for doing this. It's useless, obviously, but it's not the rank bomb it is in Garegga.
"Don't lose your medal chain": low-rank medals actually give zero rank, and there's no extra penalty for dropping one or anything like that. Not relevant! (It is sort of interesting that on the first page of this thread, Twiddle specifically says that the medal rank behavior is the same as Garegga, so I guess either he or Trap misread some data at some point...)
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If I've got something wrong, let me know, I'm no expert on this game.
And if it'd be easier, I'd be willing to make those edits to the existing text and post a revised version.