HM05 Flash in Emerald.

Flash. An HM can be taught to any number of Pokemon and the move cannot be forgotten without the Move Deleter. 155 species in Pokemon Emerald can learn it.

Bulbasaur, Ivysaur, Venusaur, Butterfree, Pikachu, Raichu, Clefairy, Clefable, Jigglypuff, Wigglytuff, Oddish, Gloom, Vileplume, Paras, Parasect, Venonat, Venomoth, Meowth, Persian, Psyduck, Golduck, Abra, Kadabra, Alakazam, Bellsprout, Weepinbell, Victreebel, Slowpoke, Slowbro, Magnemite, Magneton, Drowzee, Hypno, Voltorb, Electrode, Exeggcute, Exeggutor, Koffing, Weezing, Chansey, Tangela, Staryu, Starmie, Mr. Mime, Jynx, Electabuzz, Jolteon, Porygon, Zapdos, Mewtwo, Mew, Chikorita, Bayleef, Meganium, Hoothoot, Noctowl, Ledyba, Ledian, Spinarak, Ariados, Chinchou, Lanturn, Pichu, Cleffa, Igglybuff, Togepi, Togetic, Natu, Xatu, Mareep, Flaaffy, Ampharos, Bellossom, Hoppip, Skiploom, Jumpluff, Sunkern, Sunflora, Yanma, Wooper, Quagsire, Espeon, Umbreon, Slowking, Misdreavus, Girafarig, Shuckle, Porygon2, Stantler, Smoochum, Elekid, Blissey, Raikou, Entei, Ho-Oh, Celebi, Treecko, Grovyle, Sceptile, Beautifly, Dustox, Lotad, Lombre, Ludicolo, Seedot, Nuzleaf, Shiftry, Ralts, Kirlia, Gardevoir, Surskit, Masquerain, Shroomish, Breloom, Nincada, Ninjask, Shedinja, Skitty, Delcatty, Sableye, Meditite, Medicham, Electrike, Manectric, Plusle, Minun, Volbeat, Illumise, Roselia, Spoink, Grumpig, Spinda, Cacnea, Cacturne, Lunatone, Solrock, Baltoy, Claydol, Castform, Kecleon, Shuppet, Banette, Duskull, Dusclops, Tropius, Chimecho, Absol, Snorunt, Glalie, Metang, Metagross, Latias, Latios, Jirachi, Deoxys Normal