Pending Challenge codes - Split "Past" tag into Past Pokemon, moves, etc.

[Jumpheart]

I recently posted a thread to the Bug Reports subforum that questioned current challenge command functionality involving the "all Pokemon" tag and National Dex functionality. Following the responses there and some additional experimentation, I am making a suggestion based off of that. To tl;dr that thread and provide some extra information:

• Banning "-all Pokemon" only bans Pokemon in the current generation, not Pokemon locked to NatDex (intended functionality per Mathy)
• Using "Past" in a code bans past everything, even if other things trump it

  • /challenge gen9nationaldexubers @@@ -all pokemon, -Past, +Rattata-Alola, +all moves

  • This challenge code still has Pursuit banned, despite the fact that all moves would normally override Past
• There is no way to easily ban all past Pokemon using challenge command without banning all past items, moves, etc.

Thus, I'm suggesting something that Mathy inspired in that thread: splitting the Past tag into Past Pokemon, Past Moves, Past Items, and anything else I may be forgetting. There are a lot of niche metagames out there that Pokemon Showdown understandably cannot support with a true format, but adding these new tags would allow further customization in a way that is much easier to work with.

Per my suggestion:

• "Past" would still work as current--banning Past would work as current by banning everything not in current generation.
• "Past Pokemon" would work as the compliment to the current "All Pokemon". Banning "Past Pokemon" and "All Pokemon" should make it effectively impossible to load a team because it should ban past and present Pokemon.
• "Past Moves" would refer to all dexited moves and "Past Items" would refer to all dexited items (free berserk gene)
• They would compatible with each other in priority:

  • /challenge gen9nationaldex @@@ -Past, +Past moves

  • This code would ban all past items and Pokemon, so it would use NatDex as a base, with the legal Pokemon and items of Gen 9 tiers, but with move transfers (by being a NatDex format) and dexited moves (by re-adding Past moves).
  • Unless I am mistaken, this current functionality is impossible without manually re-adding every single dexited move in the challenge code, which is obviously less than ideal when challenge codes can already get lengthy.
    • Even if I am mistaken and it is possible, the solution is not intuitive, as I have not been able to figure it out with over an hour of trying different combinations of codes. As such, even if there is some combination that works, I believe this change should happen anyways to help make it far more intuitive and easy to navigate than the current implementation.

(Pyuk's suggestion in the thread is also an interesting alternative, about altering challenge code priority, but I am not sure what side effects it could have.)

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Also, as an aside, another quirk we found is that "-all Pokemon" has weird behavior with restrictions. If you use "-all Pokemon" and then restrict something with '*', it remains banned, even if you also specify it to be unbanned nomally.

Assume a restriction has been enabled for this challenge code:

... -all Pokemon, +Pikachu, * Pikachu, ...

Pikachu cannot be brought under this ruleset, even though it was specified to be legal. This may be something for bug reports but I'm going to bundle it into this thread for now as they're both challenge code related.