"order" of Pokémon forms is shared between unrelated species

[SnorlaxMonster]

At present, the order column of the pokemon_forms.csv is mostly just an incrementing list that groups all forms of the same species together. This makes it very inconvenient to insert new forms for pre-existing Pokémon, as every subsequent entry needs to have its order incremented.

However, while the list at first appears to be an incrementing list (with a unique value per form), this is not actually the case (as I discovered in #1532). The documentation does note

Multiple forms may have equal order, in which case they should fall back on sorting by name.

The first major group of non-unique entries is Alcremie. The Alcremie forms have distinct order values for each Cream, but each Cream shares the same order value across Sweets. So alcremie-vanilla-cream-berry-sweet is 1256 and alcremie-ruby-cream-berry-sweet is 1257, but alcremie-vanilla-cream-love-sweet is also 1256.

However, after Alcremie, there are a bunch of DLC Sword & Shield Pokémon, Hisui Pokémon, and Paldean Pokémon that share order values with Gigantamax Pokémon and forms introduced in Hisui and Paldea. Some examples:

order	Entry 1	Entry 2
1292	eternatus-eternamax	venusaur-gmax
1293	kubfu	charizard-gmax
1294	urshifu-single-strike	blastoise-gmax
1313	fuecoco	flapple-gmax
1314	crocalor	appletun-gmax
1327	rabsca	growlithe-hisui
1328	greavard	arcanine-hisui
1373	naclstack	miraidon-aquatic-mode
1374	garganacl	miraidon-glide-mode

Proposal

My proposal is that the order column do something similar to what Pokémon Champions does internally: Concatenate a National Pokédex number and a form ID to produce a unique identifier for a specific form of a Pokémon. For example, Venusaur (Pokédex #3) would be form ID 00003000, while Mega Venusaur would be form ID 00003001, and Charmander (Pokédex #4) would be form ID 0004000. (Since these are integers, the leading 0's would be stripped, but I've included them here to illustrate how the numeric identifiers are based on Pokédex numbers.)

This could even replace the existing id column of the pokemon_forms.csv table, and the order column could just be deprecated.

[jemarq04]

I definitely like the idea of using this Champions' method for producing a unique identitier, but modifying our existing IDs to match that would require an enormous refactor that I'm not sure we need. I do, however, think we should definitely update the order field (and its documentation) to use this new identifier so that things can be ordered nicely from our API! I mentioned this in the PR, but this is a great idea!

[magical]

There used to be scripts to maintain the order column, e.g. https://github.com/PokeAPI/pokedex/blob/master-pokeapi/scripts/set_pokemon_order_columns.sql

[SnorlaxMonster]

I definitely like the idea of using this Champions' method for producing a unique identitier, but modifying our existing IDs to match that would require an enormous refactor that I'm not sure we need.

That's fair. If it's just a matter of updating the foreign key in all of the tables it appears in, I think that would be reasonably doable via a script. But it looks like these ID numbers are also used as filenames in the cries and sprites submodules, and I imagine there are other more subtle places relying on these ID numbers. Maybe something to consider for API v3 (if that is ever created).

Anyway, I can certainly create a PR updating the order field in this way, since that has strong support.