Egg Groups
Each Pokémon belongs to one or two egg groups (following Stadium 2's names). It can breed with other Pokémon from the groups it belongs too. Pokémon with unknown gender (Porygon foe example) can only breed with Ditto. However, Pokémon in the "Unbreedable" group are unable to produce eggs, neither with other Pokémon from the same group nor with Ditto. Ditto cannot breed with Ditto. Also have in mind that some Pokémon may not appear in some versions. Hint: In order to find in which other group a Pokémon belongs to, do Ctrl+F and search for the Pokémon you want.
Monster
Ampharos, Bagon, Bayleef, Blastoise, Bulbasaur, Charizard, Charmander, Charmeleon, Chikorita, Croconaw, Cubone, Feraligatr, Flaaffy, Groudon, Ivysaur, Kangaskhan, Kyogre, Lapras, Larvitar, Lickitung, Luvdisc, Mareep, Marowak, Masquerain, Meganium, Nidoking, Nidoran♀, Nidoran♂, Nidorino, Pelipper, Pupitar, Rayquaza, Relicanth, Rhydon, Rhyhorn, Shelgon, Shroomish, Slowbro, Slowking, Slowpoke, Snorlax, Squirtle, Surskit, Swellow, Totodile, Tyranitar, Venusaur, Wartortle, Wingull
Water 1
Azumarill, Baltoy, Beldum, Blastoise, Corphish, Corsola, Crawdaunt, Croconaw, Delibird, Dewgong, Dragonair, Dragonite, Dratini, Electrike, Exploud, Feraligatr, Golduck, Grumpig, Hariyama, Horsea, Kabuto, Kabutops, Kingdra, Lapras, Latios, Makuhita, Manectric, Mantine, Marill, Masquerain, Metang, Minun, Octillery, Omanyte, Omastar, Plusle, Politoed, Poliwag, Poliwhirl, Poliwrath, Psyduck, Quagsire, Remoraid, Salamence, Seadra, Seel, Shroomish, Slowbro, Slowking, Slowpoke, Spinda, Squirtle, Surskit, Totodile, Trapinch, Vibrava, Wartortle, Wooper
Bug
Altaria, Ariados, Beedrill, Butterfree, Cacturne, Caterpie, Delcatty, Deoxys, Forretress, Gligar, Heracross, Kakuna, Ledian, Ledyba, Loudred, Metapod, Minun, Nincada, Ninjask, Paras, Parasect, Pineco, Pinsir, Plusle, Sableye, Scizor, Scyther, Shedinja, Shuckle, Spinarak, Swablu, Turtwig, Venomoth, Venonat, Weedle, Whismur, Yanma
Flying
Absol, Aerodactyl, Aron, Chimecho, Crobat, Dodrio, Doduo, Electrike, Farfetch'd, Fearow, Golbat, Hoothoot, Lairon, Manectric, Murkrow, Natu, Noctowl, Pidgeot, Pidgeotto, Pidgey, Skarmory, Spearow, Togetic, Xatu, Zubat
Ground
Aipom, Ampharos, Arbok, Arcanine, Azurill, Bagon, Baltoy, Barboach, Breloom, Castform, Clamperl, Corphish, Crawdaunt, Cyndaquil, Delibird, Dewgong, Diglett, Donphan, Dugtrio, Dunsparce, Duskull, Eevee, Ekans, Espeon, Farfetch'd, Flaaffy, Flareon, Furret, Gardevoir, Girafarig, Golduck, Granbull, Growlithe, Gulpin, Houndoom, Houndour, Illumise, Jolteon, Kecleon, Kirlia, Latias, Lunatone, Luvdisc, Mankey, Mareep, Medicham, Meowth, Metagross, Miltank, Nidoking, Nidoran♀, Nidoran♂, Nidorino, Ninetales, Nosepass, Persian, Phanpy, Pikachu, Piloswine, Ponyta, Primeape, Psyduck, Quagsire, Quilava, Raichu, Ralts, Rapidash, Raticate, Rattata, Registeel, Rhydon, Rhyhorn, Roselia, Sandshrew, Sandslash, Sealeo, Seel, Sentret, Shelgon, Skitty, Slaking, Slakoth, Smeargle, Sneasel, Snubbull, Solrock, Stantler, Swalot, Swinub, Tauros, Teddiursa, Typhlosion, Umbreon, Ursaring, Vaporeon, Vigoroth, Volbeat, Vulpix, Wailord, Walrein, Whiscash, Wooper
Fairy
Aggron, Anorith, Azumarill, Banette, Blissey, Chansey, Clefable, Clefairy, Cradily, Duskull, Granbull, Gulpin, Hoppip, Jigglypuff, Jirachi, Jumpluff, Marill, Meditite, Pikachu, Raichu, Roselia, Shuppet, Skiploom, Snubbull, Spheal, Togetic, Wigglytuff
Plant
Aggron, Azurill, Bayleef, Bellossom, Bellsprout, Bulbasaur, Chikorita, Claydol, Exeggcute, Exeggutor, Exploud, Gloom, Hariyama, Hoppip, Ivysaur, Jumpluff, Lileep, Makuhita, Meditite, Meganium, Nosepass, Oddish, Paras, Parasect, Relicanth, Skiploom, Skitty, Spheal, Sunflora, Sunkern, Tangela, Venusaur, Victreebel, Vileplume, Weepinbell
Humanshape
Abra, Alakazam, Claydol, Deoxys, Drowzee, Dusclops, Electabuzz, Hitmonchan, Hitmonlee, Hitmontop, Hypno, Jynx, Kadabra, Lileep, Machamp, Machoke, Machop, Magmar, Medicham, Mr. Mime, Numel, Seviper, Tropius, Turtwig, Zangoose
Water 3
Chimchar, Cloyster, Corsola, Grotle, Grumpig, Kabuto, Kabutops, Kingler, Krabby, Monferno, Omanyte, Omastar, Shellder, Spinda, Starmie, Staryu, Tentacool, Tentacruel, Torterra
Mineral
Anorith, Armaldo, Bibarel, Bidoof, Carvanha, Cradily, Electrode, Feebas, Geodude, Golem, Graveler, Magnemite, Magneton, Mawile, Onix, Porygon, Porygon2, Sharpedo, Staraptor, Steelix, Sudowoodo, Voltorb, Wailmer
Inteterminate
Bastiodon, Gastly, Gengar, Glalie, Gorebyss, Grimer, Haunter, Huntail, Infernape, Jirachi, Koffing, Magcargo, Misdreavus, Muk, Piplup, Prinplup, Regice, Regirock, Slugma, Snorunt, Weezing, Wobbuffet
Water 2
Cacnea, Camerupt, Chinchou, Flygon, Goldeen, Gyarados, Illumise, Lanturn, Latios, Magikarp, Octillery, Qwilfish, Remoraid, Seaking, Spoink, Torkoal, Volbeat
Ditto
Ditto
Dragon
Absol, Arbok, Charizard, Charmander, Charmeleon, Chimecho, Dragonair, Dragonite, Dratini, Ekans, Empoleon, Gyarados, Horsea, Kingdra, Magikarp, Pelipper, Registeel, Seadra, Staravia, Starly, Swellow, Trapinch, Vibrava, Wingull
No Eggs
Articuno, Beautifly, Blaziken, Budew, Cascoon, Celebi, Cleffa, Combusken, Cranidos, Dustox, Elekid, Entei, Grovyle, Ho-oh, Igglybuff, Kricketot, Kricketune, Linoone, Lombre, Lotad, Ludicolo, Lugia, Luxio, Luxray, Magby, Marshtomp, Mew, Mewtwo, Mightyena, Milotic, Moltres, Mudkip, Nidoqueen, Nidorina, Nuzleaf, Pichu, Poochyena, Raikou, Rampardos, Roserade, Sceptile, Seedot, Shieldon, Shiftry, Shinx, Silcoon, Smoochum, Suicune, Swampert, Taillow, Togepi, Torchic, Treecko, Tyrogue, Unown, Wurmple, Wynaut, Zapdos, Zigzagoon