diff --git a/rules/avatars.ts b/rules/avatars.ts
new file mode 100644
index 00000000..ef6b5de3
--- /dev/null
+++ b/rules/avatars.ts
@@ -0,0 +1,737 @@
+
+// The forum's auto avatars: a frozen pool of pictures it assigns to users who
+// have uploaded none. It picks one with crc32(username) % count, so the pool is
+// an index and not a set -- a name added, removed or respelled reassigns every
+// user's avatar. That is why this is a list and not a glob over the gen 5
+// sources: a sprite landing in src/ must not join the pool on its own.
+//
+// The names are the ones the 2019 set was built under, which are PS ids rather
+// than the smogon names every other set here publishes: `hooh`, not `ho-oh`.
+// publishedName(sn, psid) spells all but two of them.
+
+export let AVATARS: string[] = [
+    'abomasnow',
+    'abra',
+    'absol',
+    'accelgor',
+    'aerodactyl',
+    'aggron',
+    'aipom',
+    'alakazam',
+    'alomomola',
+    'altaria',
+    'ambipom',
+    'amoonguss',
+    'ampharos',
+    'anorith',
+    'arbok',
+    'arcanine',
+    'arceus',
+    'arceus-bug',
+    'arceus-dark',
+    'arceus-dragon',
+    'arceus-electric',
+    'arceus-ghost',
+    'arceus-grass',
+    'arceus-ground',
+    'arceus-ice',
+    'arceus-normal',
+    'arceus-poison',
+    'arceus-psychic',
+    'arceus-rock',
+    'arceus-steel',
+    'arceus-water',
+    'archen',
+    'archeops',
+    'ariados',
+    'armaldo',
+    'aron',
+    'articuno',
+    'audino',
+    'aurumoth',
+    'axew',
+    'azelf',
+    'azumarill',
+    'azurill',
+    'bagon',
+    'baltoy',
+    'banette',
+    'barboach',
+    'basculin',
+    'bastiodon',
+    'bayleef',
+    'beartic',
+    'beautifly',
+    'beedrill',
+    'beheeyem',
+    'beldum',
+    'bellossom',
+    'bellsprout',
+    'bibarel',
+    'bidoof',
+    'bisharp',
+    'blastoise',
+    'blaziken',
+    'blissey',
+    'blitzle',
+    'boldore',
+    'bonsly',
+    'bouffalant',
+    'braviary',
+    'breloom',
+    'bronzong',
+    'bronzor',
+    'budew',
+    'buizel',
+    'bulbasaur',
+    'buneary',
+    'burmy',
+    'burmy-sandy',
+    'burmy-trash',
+    'butterfree',
+    'cacnea',
+    'cacturne',
+    'camerupt',
+    'carnivine',
+    'carracosta',
+    'carvanha',
+    'cascoon',
+    'castform',
+    'castform-rainy',
+    'castform-snowy',
+    'castform-sunny',
+    'caterpie',
+    'celebi',
+    'chandelure',
+    'chansey',
+    'charizard',
+    'charmander',
+    'charmeleon',
+    'chatot',
+    'cherrim',
+    'cherrim-sunshine',
+    'cherubi',
+    'chikorita',
+    'chimchar',
+    'chimecho',
+    'chinchou',
+    'chingling',
+    'cinccino',
+    'clamperl',
+    'claydol',
+    'clefable',
+    'clefairy',
+    'cleffa',
+    'cloyster',
+    'cobalion',
+    'cofagrigus',
+    'combee',
+    'combusken',
+    'conkeldurr',
+    'corphish',
+    'corsola',
+    'cottonee',
+    'cradily',
+    'cranidos',
+    'crawdaunt',
+    'cresselia',
+    'croagunk',
+    'crobat',
+    'croconaw',
+    'crustle',
+    'cryogonal',
+    'cubchoo',
+    'cubone',
+    'cyndaquil',
+    'darkrai',
+    'darmanitan',
+    'darmanitan-zen',
+    'darumaka',
+    'deerling',
+    'deerling-autumn',
+    'deerling-summer',
+    'deerling-winter',
+    'deino',
+    'delcatty',
+    'delibird',
+    'deoxys',
+    'deoxys-attack',
+    'deoxys-defense',
+    'deoxys-speed',
+    'dewgong',
+    'dewott',
+    'dialga',
+    'diglett',
+    'ditto',
+    'dodrio',
+    'doduo',
+    'donphan',
+    'dragonair',
+    'dragonite',
+    'drapion',
+    'dratini',
+    'drifblim',
+    'drifloon',
+    'drilbur',
+    'drowzee',
+    'druddigon',
+    'ducklett',
+    'dugtrio',
+    'dunsparce',
+    'duosion',
+    'durant',
+    'dusclops',
+    'dusknoir',
+    'duskull',
+    'dustox',
+    'dwebble',
+    'eelektrik',
+    'eelektross',
+    'eevee',
+    'ekans',
+    'electabuzz',
+    'electivire',
+    'electrike',
+    'electrode',
+    'elekid',
+    'elgyem',
+    'emboar',
+    'emolga',
+    'empoleon',
+    'entei',
+    'escavalier',
+    'espeon',
+    'excadrill',
+    'exeggcute',
+    'exeggutor',
+    'exploud',
+    'farfetchd',
+    'fearow',
+    'feebas',
+    'feraligatr',
+    'ferroseed',
+    'ferrothorn',
+    'finneon',
+    'flaaffy',
+    'flareon',
+    'floatzel',
+    'flygon',
+    'foongus',
+    'forretress',
+    'fraxure',
+    'frillish',
+    'froslass',
+    'furret',
+    'gabite',
+    'gallade',
+    'galvantula',
+    'garbodor',
+    'garchomp',
+    'gardevoir',
+    'gastly',
+    'gastrodon',
+    'gastrodon-east',
+    'genesect',
+    'gengar',
+    'geodude',
+    'gible',
+    'gigalith',
+    'girafarig',
+    'giratina',
+    'giratina-origin',
+    'glaceon',
+    'glalie',
+    'glameow',
+    'gligar',
+    'gliscor',
+    'gloom',
+    'golbat',
+    'goldeen',
+    'golduck',
+    'golem',
+    'golett',
+    'golurk',
+    'gorebyss',
+    'gothita',
+    'gothitelle',
+    'gothorita',
+    'granbull',
+    'graveler',
+    'grimer',
+    'grotle',
+    'groudon',
+    'grovyle',
+    'growlithe',
+    'grumpig',
+    'gulpin',
+    'gurdurr',
+    'gyarados',
+    'happiny',
+    'hariyama',
+    'haunter',
+    'haxorus',
+    'heatmor',
+    'heatran',
+    'heracross',
+    'herdier',
+    'hippopotas',
+    'hippowdon',
+    'hitmonchan',
+    'hitmonlee',
+    'hitmontop',
+    'honchkrow',
+    'hooh',
+    'hoothoot',
+    'hoppip',
+    'horsea',
+    'houndoom',
+    'houndour',
+    'huntail',
+    'hydreigon',
+    'hypno',
+    'igglybuff',
+    'illumise',
+    'infernape',
+    'ivysaur',
+    'jellicent',
+    'jigglypuff',
+    'jirachi',
+    'jolteon',
+    'joltik',
+    'jumpluff',
+    'jynx',
+    'kabuto',
+    'kabutops',
+    'kadabra',
+    'kakuna',
+    'kangaskhan',
+    'karrablast',
+    'kecleon',
+    'keldeo',
+    'keldeo-resolute',
+    'kingdra',
+    'kingler',
+    'kirlia',
+    'klang',
+    'klink',
+    'klinklang',
+    'koffing',
+    'krabby',
+    'kricketot',
+    'kricketune',
+    'krokorok',
+    'krookodile',
+    'kyogre',
+    'kyurem',
+    'kyurem-black',
+    'kyurem-white',
+    'lairon',
+    'lampent',
+    'landorus',
+    'landorus-therian',
+    'lanturn',
+    'lapras',
+    'larvesta',
+    'larvitar',
+    'latias',
+    'latios',
+    'leafeon',
+    'leavanny',
+    'ledian',
+    'ledyba',
+    'lickilicky',
+    'lickitung',
+    'liepard',
+    'lileep',
+    'lilligant',
+    'lillipup',
+    'linoone',
+    'litwick',
+    'lombre',
+    'lopunny',
+    'lotad',
+    'loudred',
+    'lucario',
+    'ludicolo',
+    'lugia',
+    'lumineon',
+    'lunatone',
+    'luvdisc',
+    'luxio',
+    'luxray',
+    'machamp',
+    'machoke',
+    'machop',
+    'magby',
+    'magcargo',
+    'magikarp',
+    'magmar',
+    'magmortar',
+    'magnemite',
+    'magneton',
+    'magnezone',
+    'makuhita',
+    'malaconda',
+    'mamoswine',
+    'manaphy',
+    'mandibuzz',
+    'manectric',
+    'mankey',
+    'mantine',
+    'mantyke',
+    'maractus',
+    'mareep',
+    'marill',
+    'marowak',
+    'marshtomp',
+    'masquerain',
+    'mawile',
+    'medicham',
+    'meditite',
+    'meganium',
+    'meloetta',
+    'meloetta-pirouette',
+    'meowth',
+    'mesprit',
+    'metagross',
+    'metang',
+    'metapod',
+    'mew',
+    'mewtwo',
+    'mienfoo',
+    'mienshao',
+    'mightyena',
+    'milotic',
+    'miltank',
+    'mimejr',
+    'minccino',
+    'minun',
+    'misdreavus',
+    'mismagius',
+    'mollux',
+    'moltres',
+    'monferno',
+    'mothim',
+    'mrmime',
+    'mudkip',
+    'muk',
+    'munchlax',
+    'munna',
+    'murkrow',
+    'musharna',
+    'natu',
+    'necturna',
+    'nidoking',
+    'nidoqueen',
+    'nidoranf',
+    'nidoranm',
+    'nidorina',
+    'nidorino',
+    'nincada',
+    'ninetales',
+    'ninjask',
+    'noctowl',
+    'nosepass',
+    'numel',
+    'nuzleaf',
+    'octillery',
+    'oddish',
+    'omanyte',
+    'omastar',
+    'onix',
+    'oshawott',
+    'pachirisu',
+    'palkia',
+    'palpitoad',
+    'panpour',
+    'pansage',
+    'pansear',
+    'paras',
+    'parasect',
+    'patrat',
+    'pawniard',
+    'pelipper',
+    'persian',
+    'petilil',
+    'phanpy',
+    'phione',
+    'pichu',
+    'pidgeot',
+    'pidgeotto',
+    'pidgey',
+    'pidove',
+    'pignite',
+    'pikachu',
+    'piloswine',
+    'pineco',
+    'pinsir',
+    'piplup',
+    'plusle',
+    'politoed',
+    'poliwag',
+    'poliwhirl',
+    'poliwrath',
+    'ponyta',
+    'poochyena',
+    'porygon',
+    'porygon2',
+    'porygonz',
+    'primeape',
+    'prinplup',
+    'probopass',
+    'psyduck',
+    'pupitar',
+    'purrloin',
+    'purugly',
+    'quagsire',
+    'quilava',
+    'qwilfish',
+    'raichu',
+    'raikou',
+    'ralts',
+    'rampardos',
+    'rapidash',
+    'raticate',
+    'rattata',
+    'rayquaza',
+    'regice',
+    'regigigas',
+    'regirock',
+    'registeel',
+    'relicanth',
+    'remoraid',
+    'reshiram',
+    'reuniclus',
+    'rhydon',
+    'rhyhorn',
+    'rhyperior',
+    'riolu',
+    'roggenrola',
+    'roselia',
+    'roserade',
+    'rotom',
+    'rotom-heat',
+    'rotom-mow',
+    'rotom-wash',
+    'rufflet',
+    'sableye',
+    'salamence',
+    'samurott',
+    'sandile',
+    'sandshrew',
+    'sandslash',
+    'sawk',
+    'sawsbuck',
+    'sawsbuck-autumn',
+    'sawsbuck-summer',
+    'sawsbuck-winter',
+    'sceptile',
+    'scizor',
+    'scolipede',
+    'scrafty',
+    'scraggy',
+    'scyther',
+    'seadra',
+    'seaking',
+    'sealeo',
+    'seedot',
+    'seel',
+    'seismitoad',
+    'sentret',
+    'serperior',
+    'servine',
+    'seviper',
+    'sewaddle',
+    'sharpedo',
+    'shaymin',
+    'shaymin-sky',
+    'shedinja',
+    'shelgon',
+    'shellder',
+    'shellos',
+    'shellos-east',
+    'shelmet',
+    'shieldon',
+    'shiftry',
+    'shinx',
+    'shroomish',
+    'shuckle',
+    'shuppet',
+    'sigilyph',
+    'silcoon',
+    'simipour',
+    'simisage',
+    'simisear',
+    'skarmory',
+    'skiploom',
+    'skitty',
+    'skorupi',
+    'skuntank',
+    'slaking',
+    'slakoth',
+    'slowbro',
+    'slowking',
+    'slowpoke',
+    'slugma',
+    'smeargle',
+    'smoochum',
+    'sneasel',
+    'snivy',
+    'snorlax',
+    'snorunt',
+    'snover',
+    'snubbull',
+    'solosis',
+    'solrock',
+    'spearow',
+    'spheal',
+    'spinarak',
+    'spinda',
+    'spiritomb',
+    'spoink',
+    'squirtle',
+    'stantler',
+    'staraptor',
+    'staravia',
+    'starly',
+    'starmie',
+    'staryu',
+    'steelix',
+    'stoutland',
+    'stunfisk',
+    'stunky',
+    'substitute',
+    'sudowoodo',
+    'suicune',
+    'sunflora',
+    'sunkern',
+    'surskit',
+    'swablu',
+    'swadloon',
+    'swalot',
+    'swampert',
+    'swanna',
+    'swanna-2',
+    'swellow',
+    'swinub',
+    'swoobat',
+    'taillow',
+    'tangela',
+    'tangrowth',
+    'tauros',
+    'teddiursa',
+    'tentacool',
+    'tentacruel',
+    'tepig',
+    'terrakion',
+    'throh',
+    'thundurus',
+    'thundurus-therian',
+    'timburr',
+    'tirtouga',
+    'togekiss',
+    'togepi',
+    'togetic',
+    'tomohawk',
+    'torchic',
+    'torkoal',
+    'tornadus',
+    'tornadus-therian',
+    'torterra',
+    'totodile',
+    'toxicroak',
+    'tranquill',
+    'trapinch',
+    'treecko',
+    'tropius',
+    'trubbish',
+    'turtwig',
+    'tympole',
+    'tynamo',
+    'typhlosion',
+    'tyranitar',
+    'tyrogue',
+    'umbreon',
+    'unfezant',
+    'unown',
+    'ursaring',
+    'uxie',
+    'vanillish',
+    'vanillite',
+    'vanilluxe',
+    'vaporeon',
+    'venipede',
+    'venomoth',
+    'venonat',
+    'venusaur',
+    'vespiquen',
+    'vibrava',
+    'victini',
+    'victreebel',
+    'vigoroth',
+    'vileplume',
+    'virizion',
+    'volbeat',
+    'volcarona',
+    'voltorb',
+    'vullaby',
+    'vulpix',
+    'wailmer',
+    'wailord',
+    'walrein',
+    'wartortle',
+    'watchog',
+    'weavile',
+    'weedle',
+    'weepinbell',
+    'weezing',
+    'whimsicott',
+    'whirlipede',
+    'whiscash',
+    'whismur',
+    'wigglytuff',
+    'wingull',
+    'wobbuffet',
+    'woobat',
+    'wooper',
+    'wormadam',
+    'wormadam-sandy',
+    'wormadam-trash',
+    'wurmple',
+    'wynaut',
+    'xatu',
+    'yamask',
+    'yanma',
+    'yanmega',
+    'zangoose',
+    'zapdos',
+    'zebstrika',
+    'zekrom',
+    'zigzagoon',
+    'zoroark',
+    'zorua',
+    'zubat',
+    'zweilous',
+];
+
+// Two names the 2019 tree carried a second copy of. Swanna's two files were
+// byte for byte the same picture; Arceus and Arceus-Normal were two palettes of
+// one pose, and only the one is drawn today. Both spend their slot on the
+// picture already in the pool.
+export let AVATAR_ALIASES: Record<string, string> = {
+    'arceus-normal': 'arceus',
+    'swanna-2': 'swanna',
+};
+
+// The pool in the order the forum indexes it, which is the directory listing
+// scandir() used to return. Two things about that listing are the index and so
+// are reproduced rather than tidied away: it sorted filenames with the
+// extension attached, which orders `arceus-bug.gif` ahead of `arceus.gif` where
+// the bare names sort the other way round, and it led with `.` and `..`, which
+// named no avatar but counted toward the divisor. Those two slots rendered a
+// broken image; they get Substitute, which the pool already carries, so they
+// cost nothing but the slot.
+export function avatarSlots(): string[] {
+    let files = [...AVATARS].sort((a, b) => `${a}.gif` < `${b}.gif` ? -1 : 1);
+    return ['substitute', 'substitute', ...files];
+}
diff --git a/rules/publish.ts b/rules/publish.ts
index a7c6c41a..d5e27300 100644
--- a/rules/publish.ts
+++ b/rules/publish.ts
@@ -55,10 +55,20 @@ export class Manifest {
         this.#ctx.copy(f, `${this.#tree.root}/${dir}/${stamped}`);
     }
 
+    // The whole url the copy `name` answers to. Exposed on its own for a set
+    // that publishes some other projection of this mapping than write()'s.
+    url(name: string): string {
+        let e = this.#entries.get(name);
+        if (e === undefined) {
+            throw new Error(`no sprite named ${name}`);
+        }
+        return `${this.#tree.served}/${e.dir}/${e.stamped}`;
+    }
+
     write(dst: string): void {
         let sorted: Record<string, string> = {};
-        for (let [k, e] of this.#sorted()) {
-            sorted[k] = `${this.#tree.served}/${e.dir}/${e.stamped}`;
+        for (let [k] of this.#sorted()) {
+            sorted[k] = this.url(k);
         }
         this.#ctx.write(dst, JSON.stringify(sorted, null, 4) + '\n');
     }
diff --git a/smogon.build.ts b/smogon.build.ts
index 914148aa..1ba26310 100644
--- a/smogon.build.ts
+++ b/smogon.build.ts
@@ -1,9 +1,12 @@
 
+import * as spritedata from '@smogon/sprite-data/index.ts';
+
+import {AVATARS, AVATAR_ALIASES, avatarSlots} from './rules/avatars.ts';
 import {gen10Modelslike} from './rules/modelslike.ts';
 import {GEN4_CAPS, forEachFront, fronts, named} from './rules/oldgen.ts';
 import {Manifest, type Sprite, type Tree, firstWins, itemspritecopy, spritecopy} from './rules/publish.ts';
-import {type CmdSpec, forEachRule, rule} from './tools/build/artifact.ts';
-import {compresspng, pad, spriteglob, trimimg} from './tools/build/helpers.ts';
+import {type Artifact, type CmdSpec, forEachRule, rule} from './tools/build/artifact.ts';
+import {base, compresspng, pad, spriteglob, trimimg} from './tools/build/helpers.ts';
 import {type DeployCtx, deploy} from './tools/deploy/api.ts';
 
 // The tar root maps onto the served tree: sprites/x is served at
@@ -220,6 +223,60 @@ deploy(async ctx => {
     manifest.write('__meta/forumsprites/manifest.json');
 });
 
+// Forum auto avatars: the gen 5 animations on a uniform 96x96 box, which is
+// what XenForo's avatar container is. It scales an <img> to fill, so a sprite
+// published at its own aspect would arrive stretched; the box is the games' own
+// sprite size, so nothing is scaled up, and the few animations that overflow it
+// are cropped to it, which is what the set the forum used to carry did too.
+
+// The pool with its two second slots resolved, which is the set of pictures to
+// build. See rules/avatars.ts for why it is a list and not a glob.
+let avatarPool = new Set(AVATARS.map(name => AVATAR_ALIASES[name] ?? name));
+
+let avatarArt = new Map<string, Artifact>();
+for (let f of spriteglob(['src/sprites/gen5/*.gif', 'src/sprites/gen5/xsubstitute.png'],
+                         {b: false, s: false})) {
+    // publishedNames() is no use here: it resolves smogon names where the pool
+    // is spelled in PS ids, and it refuses the one x-kind sprite the pool
+    // carries. Backs and shinies are filtered above rather than here, since
+    // publishedName spells them exactly as it spells their front.
+    let name = spritedata.publishedName(spritedata.parseFilename(base(f)), spritedata.psid);
+    if (!avatarPool.has(name)) {
+        continue;
+    }
+    if (avatarArt.has(name)) {
+        throw new Error(`avatar ${name}: two gen 5 sources publish it`);
+    }
+    avatarArt.set(name, rule(f, {
+        display: 'avatar %f',
+        cmds: [
+            'magick convert %f -coalesce -background none -gravity center -extent 96x96 %o',
+            'gifsicle -O3 -b %o',
+        ],
+    }, `${name}.gif`));
+}
+
+// A pool member with no source would leave the forum a shorter list and
+// reassign every user, so a source renamed out from under one fails the build
+// rather than the deploy.
+for (let name of avatarPool) {
+    if (!avatarArt.has(name)) {
+        throw new Error(`avatar ${name}: no gen 5 source`);
+    }
+}
+
+deploy(async ctx => {
+    let manifest = new Manifest(ctx, TREE);
+    for (let [name, art] of avatarArt) {
+        await manifest.copy(art, {dir: 'avatars'}, name);
+    }
+    // Published by slot rather than by name: nothing looks an avatar up, the
+    // forum picks one with crc32(username) % count, so the order is the whole
+    // mapping and the length is the divisor.
+    let slots = avatarSlots().map(name => manifest.url(AVATAR_ALIASES[name] ?? name));
+    ctx.write('__meta/avatars/manifest.json', JSON.stringify(slots, null, 4) + '\n');
+});
+
 // PMD sprites ship as-is, stamped.
 
 deploy(async ctx => {