Filenames
<kind><name>[-o<forme>][-<flag>...].<ext>
<kind> is s for a species, i for an item, or x for something the games
don't name (xegg, xsubstitute, xarceusunknown), so a directory can hold
more than one and rules can match them apart.
<name> is the name with its case and punctuation flattened away, keeping only
where the words divide: a run of non-alphanumerics becomes _ when it separates
words and disappears otherwise. Ho-Oh is sho_oh, Mr. Mime is smr_mime,
Farfetch’d is sfarfetchd, Flabébé is sflabebe. Keeping the divisions is
what lets the two places these sprites are published each spell a name their own
way, smogon as ho-oh and PS as hooh, with nothing having to look it up.
Formes ride in -o, so Charizard-Mega-X's back sprite is
scharizard-omega_x-b.gif and every Charizard is scharizard-*. The forme
comes first so a forme's sprites sort together.
Flags
Beyond the per-directory flags below:
-oForme-aAsymmetrical, faces the wrong way and needs flipping-cWhich of several identical formes, where pokemon-showdown gives one name to more than one of the games' forme slots (Zygarde's Power Construct pair, Minior's seven meteors)
sprites/gen1
PNG original dimensions 40x40, 48x48, or 56x56 for fronts; 32x32 for backs
Sprites in the main directory use Super Game Boy palettes, and those in /gbc use Game Boy Color palettes
-bBack sprite-gGame it is from, can berb,rg,rgb, oryrbis Red and Blue,rgis Japanese Red and Green,rgbis Red, Green, and Blue, andyis Yellow
sprites/gen2
PNG original dimensions 40x40, 48x48, or 56x56 for fronts; 48x48 for backs
-bBack sprite-sShiny-gGame it is from, can beg,s,c,gs,gc,sc, orgscgis Gold,sis Silver, andcis Crystal
sprites/gen3
PNG original dimensions 64x64
-bBack sprite-sShiny-gGame it is from, can ber,f,l,e,re,fe, orrferis Ruby and Sapphire,fis Fire Red,lis Leaf Green, andeis Emerald- Except for Deoxys Attack, all Fire Red sprites are also used in Leaf Green
sprites/gen4
PNG original dimensions 80x80
-bBack sprite-fFemale-sShiny-gGame it is from, can bed,p,h,dp,dh,ph, ordphdis Diamond and Pearl,pis Platinum, andhis HeartGold and SoulSilver
models, dex, afd, previews
-bBack sprite-sShiny-gGmax-fFemale
minisprites/pokemon
/gen8, /lgpe - PNG original dimensions 68x56
/home - PNG original dimensions 128x128
/bdsp - PNG original dimensions 256x256
-gGmax-fFemale-vVendor is someone else than the official games, can besmogon(documentduplicateandg5?)