re: Alola, Sol y Luna
(aka This D!post)
Here's what little input I have on these matters, given that I have not played the games in full. (I'm still in the second island, enjoying the view)
In General Terms
I'm pro keeping us as a RP separate of which game of any would be "canon", mostly because I like the concept that we are our own thing. We need not to follow minutes introduced in the games / other parts of the franchise to a point that is constricting, given pretty much our entire point as an RP is to do the opposite.
Also because of that, I suggest we refrain from overwriting the canon game plots with our own. Meaning, the Sol/Luna protags as well as the various canon characters such as Lusamine did their thing if possible. We'd enter the picture either after that or as a joint / side action.
Tapus
I'm ambivalent over what do we do with them, but I'd suggest we meet halfways the options re: their dialogue possibilities, and say they can only speak directly "to Protagonists" (aka: Player Characters, canon PCs, etc). That also gives them a bit more of a mythical vibe that I personally like them having.
That does introduce the issue of Secondary Characters not being able to speak with them, but at the same time provides both a good opportunity and a good motive to use the Armbands or review other means in story if required.
Solleón y Allunara
Re: What do we do with their plot-relevant special location, I'm more partial to Lake of Moone + Altar of Sunne, if that can happen. If not, I suggest we mix and match the locations given what we did with G5.
The Æther Foundation (ÆF) and PEFE
Unless there's specific reason not to in terms of established worldbuilding, I'd suggest to have ÆF not have had serious / longstanding dealings with Pokéfutures and or PEFE in the past, but still have collaborated or competed in minor things. The main motivation I'd have behind this is detailed below, but this does also help us introduce minor characters and NPCs as having worked with ÆF without information or motivation issues, including reworking the backstories of secondary characters if their players deem it adequate.
Type: Null in short supply
Given there's an artificial limitation in the amount of them, I'd heavily suggest we follow that plotline. Taking advantage of eg.: making an alliance between ÆF and PEFE, I'd say let's keep the three in their current status, so no access for players, under the guise of ÆF and PEFE doing joint work in testing the third specimen for later production. That way, when the sequels / Stars / Eclipse / 4makes come and there likely is a new canon way to get access to a Type: Null, we can incorporate them much more easily. If the $NEXT_GAMES are taking too long to come or it's looking like they'll just sidestep the Type: Null shortage issue, then we can just fall back to our solution and have PEFE / ÆF release a first batch of Type: Nulls to the player characters for testing.
Presumably, this means Type: Nulls will not be allowed to take part in League-sanctioned battles for some time.
Yes, I'm aware that this proposal means no access for now. Yes, I think that is fairer for the entire playerbase given that's what we do anyways with mons who are one of a kind for the most part (eg.: Legendaries).
Dimensional Breaking
Due to issues of balance, I'd suggest to refrain players and signups from having "Faller" as part of their backstory. It can be examined as a future element, but having suddenly player characters who come from other universes, which themselves follow potentially different foundational rules of physics and stuff, can easily lead to godmodding, specialness and unneeded meta conflict.
In the future, as the generations come and go and these issues are better examined both in canon and in the meta, we might be able to change that, though I do not see the point of it.
Regarding the potential of Ultra Beasts appearing elsewhere in the world than Alola, I do not see a strong point against it. In fact, I'd surmise given the particular of dimensional breaking established in canon, they should be likely to also pop up in Sinnoh as well (hint hint 4makes cough cough).
Z-Moves in Battle
Re: using the Z-moves, I'd go with the second option of limiting to being used from a move the Pokemon's already used in-battle. Of course, in battles without the 4-moves limit we would discard that rule, though I'd suggest that for some time and as a form of testing and balancing, use of Z-Moves in battles without the 4-moves limit is publicly arranged by the involved players themselves in the meta.
Anabel Issues
While I'm mostly uninformed and choose to remain that way for some time as I play the game, I'm partial to whichever proposed solution does not break neither WAAPT canon nor game canon. Meaning, presumably, there would be two Anabels around, and IMO if possible in our 'verse the Game!Anabel should eventually be returned to her origin universe.
Champion Issues
Given that we do not intersect with the games plot, I do not see immediate harm in having an undetermined one of the canon PC's becoming the Champion. Kukui himself is a good second option. If the playerbase is OK with moving Jacob's title over that would be okay-ish as well I guess, as I have pending conversations to canonize RP!Silent as (surogate) Champion in his origin region.
Whichever way is chosen, it just needs to be kept track of so that players who go battle the Champion don't battle different Champions unless there's in-universe reason to.
Mega Dark
I personally like the whole deal with the Mega Evolutions now being given a darker, in certain ways more monstruous spin, and I personally feel it vibes well with my HC that Mega Evolution is basically Shadow but rebranded and remarketed "for good". But I've read that certain 'dex entries kinda take it too far and then again we are taking descriptions from a possessed Pokédex, so I'm more partial towards hinting more negative consequences (and motivations) for Mega Evolution, such as Heroic RRODs and having the mons actually have to spend time at the infirmary / rehab, rather than going full grimdark.
WAAPT Timeline
This is one of those cases where I strongly point to my "We Are Not The Games" intro. If we go with the canon story of Sol y Luna having happened mostly as depicted, there is no harm in coming late to the party, we'll just have to figure out the story. However, that is assuming we want to retain full "Real Time" flow of the RP, which is something I've read it has been contested a couple of times during discussion among the playerbase.
Haunted Pokédexes
Given we already have PEFEdexes and PEFEgons, I'd say a haunted Pokédex should not be too outside of the norm, if I guess we won't be able to expect them to work "correctly" right off the bat. Meaning: issues with compatibility or right out trolling will conveniently arise that help us with our plots :p
Ash-Greninja
I'd rather we keep ourselves far away from that specific transformation, in that hopefully Ash doesn't exist here, but I'm okay with developing our own character-specific transformations if it's accorded by the playerbase and it's not limited to Greninja. In a certain way, it would not be really any different from what we already do with stuff like custom moves. However, they will have to be checked for (faux, given their status)-balance at the meta.
“Thou hast forgotten the face of thy Lord. Remember, mortal, and fear pet me.”