What are Horde Encounters in Pokemon X and Y?

Answer 1

Horde Encounters are a new mode of battle, in which 5 pokemon appear at once. These pokemon are generally lower levelled than those found in the standard battles of the immediate area.

In these battles, your one Pokemon can fight against 5 opponents. After your Pokemon attacks, it must withstand the attacks of all 5 of its opponents. Rock Slide has been confirmed to damage all 5 opponents at the same time.

Answer 2

You can see below all the Pokémon that may appear in Hordes in Pokémon X and Y and their respective location. A Pokémon species may be found in more than one place and some are exclusive to the version you own.

Route 5 - Plusle, Minun, Gulpin and Scraggy;

Route 7 - Psyduck, Hoppip and Roselia;

Route 8 - Taillow, Wingull, Zangoose and Seviper;

Route 10 - Yanma, Houndour (X), Nosepass and Electrike (Y);

Route 11 - Nidoran♀, Nidoran♂, Starly and Stunky;

Route 12 - Tauros, Mareep, Miltank and Wingull;

Route 14 - Ekans, Bellsprout and Skorupi;

Route 15 & 16 - Murkrow, Foongus and Klefki;

Route 18- Geodude, Heatmor and Durant;

Route 19 - Arbok, Weepinbell, Gligar and Skorupi;

Route 20 - Sudowoodo, Trevenant and Foongus;

Route 21 - Scyther, Spinda and Swablu;

Azure Bay - Wingull, Slowpoke and Exeggcute;

Connecting Cave - Zubat, Whismur and Axew;

Reflection Cave - Mime Jr., Roggenrola and Carbink;

Frost Cavern - Smoochum, Vanillite and Cubchoo;

Terminus Cave - Aron (X), Larvitar (Y), Geodude and Durant;

Pokémon Village - Poliwag, Noctowl, Lombre and Foongus;

Victory Road - Lickitung, Graveler, Geodude and Floatzel.