- Plusle, Route 5.
- Minun, Route 5.
- Gulpin, Route 5.
- Scraggy, Route 5.
- Psyduck, Route 7.
- Hoppip, Route 7.
- Roselia, Route 7.
- Taillow, Route 8.
- Wingull, Azure Bay.
- Zangoose, Route 8.
- Seviper, Route 8.
- Yanma, Route 10.
- Houndour, Route 10.
- Nosepass, Route 10.
- Electrike, Route 10. (Y only)
- Nidoran (both genders), Route 10.
- Starly, Route 10.
- Stunky, Route 11.
- Tauros, Route 12.
- Mareep, Route 12.
- Miltank, Route 12.
- Ekans, Route 14.
- Bellsprout, Route 14.
- Skorupi, Route 14 and Route 19.
- Murkrow, Route 15 and Route 16.
- Foongus, Routes 15, 16, 20 and the Pokemon Village.
- Klefki, Route 15 and Route 16.
- Geodude, Route 18, Terminus Cave and Victory Road.
- Heatmor, Route 18.
- Durant, Route 18 and Terminus Cave.
- Arbok, Route 19.
- Weepinbell, Route 19.
- Gligar, Route 19.
- Sudowoodo, Route 20.
- Trevenant, Route 20.
- Scyther, Route 21.
- Spinda, Route 21.
- Swablu, Route 21.
- Whismur, Connecting Cave.
- Axew, Connecting Cave.
- Mime Jr., Reflection Cave.
- Roggenrola, Reflection Cave.
- Carbink, Reflection Cave.
- Smoochum, Frost Cavern.
- Vanillite, Frost Cavern.
- Cubchoo, Frost Cavern.
- Aron, Terminus Cave.
- Larvitar, Terminus Cave. (Y only)
- Poliwag, Pokemon Village.
- Noctowl, Pokemon Village.
- Lombre, Pokemon Village.
- Lickitung, Victory Road.
- Graveler, Victory Road.
- Floatzel, Victory Road.
- Slowpoke, Azure Bay.
- Exeggcute, Azure Bay.
There are also certain hordes that will consist of different Pokemon, a 4/5 Pokemon in the horde will be one species, while 1/5 of the horde will be another. Some of these Pokemon are enemy Pokemon, and will try attack the one of the opposing species before trying to attack you.
The Pokemon with (X) after it will have 4/5 Pokemon of that species in that game whenever you encounter the horde, the Pokemon with (Y) after it will be the same except in Pokemon Y.
- Plusle (X), Minun (Y)
- Zangoose (X), Seviper (Y)
- Male Nidoran (X), Female Nidoran (Y)
- Durant (X), Heatmor (Y)
- Tauros (X), Miltank (Y)
- Trevanent (X), Sudowoodo (Y)
- Roggenrola (X), Carbink (Y)
I made an answer because the first one was badly copied. :/
Hope I helped. :)
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