rules explanation

The rule about online etiquette is expanded to mention offensive, explicit, spam and troll posts, and also includes info about format overuse as this fits within this category and I don't think it requires its own rule.
The rule about duplicate posts also mentions "necroposts" or bumping old stuff for no reason. This rule means people know not to clog the activity feed with anything unnecessary. We hide comments on old posts for being unhelpful quite often.
"Post on the correct section" is listed as a formal rule; as I mentioned above, I listed anything I would hide a post for. I would hide a post for being on the wrong section, so I think it should be included for clarity.
I condensed a number of rules into "make your posts informative". This means proper tags and descriptive titles aren't their own rules -- these are quite self explanatory and don't require too much detail in my opinion. This rule also makes reservation for us to hide posts for being incorrect (which we must do until a "mark unresolved" feature is added) or for being off-topic. This rule also gives us grounds to remove posts that are explained poorly and don't really provide an answerable question.
I condensed "don't post big images" and "don't put too many images on moveset threads" into one rule. They are related to each other and are better remembered together in my opinion.
I included a rule about the site's moderation, which encourages people not to answer rule-breaking posts and not to "mini-mod" (just flag instead).
"Don't copy paste directly" is changed to "your posts should be your content". This gives us more room to hide posts for being blatant plagiarism, and encourages people to credit their sources.
"Respect the points system" is added as a rule. This gives us the ability to warn users for "buddy voting" based on the rules. (Sure it's a bit obvious, but the message doesn't get across well to the site's younger demographic in particular and deserves mention.)
A formal rule is added about silly or unreasonable questions. Unfortunately people sometimes like to make dumb posts like this one that wouldn't appear to break the rules otherwise. Additionally, this gives us grounds to take down posts whose answers are not presently known -- it also mentions that "is [x] known" is a better question than "what is [x]".
I added a rule that asks users to follow guidelines prescribed in the original post. Again this should be a comprehensive list of reasons why we would take things down, and I would take down a moveset post for now following the guidelines linked in the original post.
There is a rule listed about not making duplicate accounts. This has been necessary for years, and should absolutely receive some mention in the rules.
The "no polls/ opinions" rule is expanded to more broadly cover posts that are open-ended, discussion-based or have too many different valid answers. I also included a note underneath it that outlines how questions openly asking for advice on movesets and in-game teams are subject to this rule, and which of these will be allowed (eg. "I need a Pokemon for my team that can do [x, y]" can be allowed, "rate my [game] team" cannot).
The rule about "trivial" or simple posts is removed. I've never really liked this rule much. It's there for a reason sure, but I don't think it's really enough to warrant taking posts down. These don't come about often and when they do, they can be resolved very quickly and sent down the activity list. They're not much of a bother, and sometimes they come about because people don't know where to look in the first place. They're also good to get PokeBase into Google. This rule is also blurred since the site contains info on some things, but is missing others (Gen 7 generally), which makes it increasingly unhelpful and irritating to enforce.
The rules about in-game teams and movesets are combined and placed under "PokeBase rules". These are remembered better together in my opinion. I've also included an additional note that makes it clear that no exceptions are made. People tend to think if there is no answer for a specific nature for example, they can post a thread about it, which would make the site awfully cluttered and distribute sets across multiple pages which is impractical.
The rules about ROMs and unofficial games are combined, as I think they are remembered better together. Additionally, they mention that discussion of modification is not allowed (eg. how to inject Pokemon with PokeGen and the like).
Several meta rules are combined into a broader "be specific" rule that more quickly goes over everything needed in meta posts. Though I understand how the extended detail is may be necessary in this case, just maybe not all as separate rules.
"No announcements" and "no posts about down voting" are combined into "no trivial posts". Ultimately that's the reason those are taken down, they're of little consequence and basically become clutter.
TCG decks are given specific mention in the Battle Subway's rules. There are many TCG posts on the RMT section, they should be acknowledged.
Battle Subway rules outline what an in-game team is and makes it very clear they are not allowed, and maintains that Battle Tree etc. is an exception.
The rule about including all detail mentions that posts should mention their format and whether or not they use Smogon rules. Those who frequent the Battle Subway section have asked for this for a while.
The rule about full teams more broadly covers anything that is more focused on teambuilding and mentions that any incomplete teams should describe ideas for what the last additions could be.
Some non-rules about how you should know the basics of Pokemon were left out, as explained above. If you can get past including your Pokemon's EVs or roles, you know what physical and special is. I also left out the rule about only answering if you have substantial detail to give, since that is already described by the global rule that says to only answer if you can fully resolve the question.
The rules for the chat room are condensed into one simple rule. Some others were moved into the first rule about online etiquette, since spam and such isn't welcome anywhere.