ORAS EV Training Hot Spots (Hordes)

A well known, effective way of EV training is horde battling.

Using the move Sweet Scent in certain routes, you have a 100% chance of getting a horde battle, meaning you can easily defeat 5 Pokémon which gives EVs on the same stats with a multi-targeting move, such as surf or earthquake, and if you are using the EXP Share, your entire team will benefit.
(I highly recommend using the Pokémon Tropius as your horde battler, since it can learn a variety of multi-targeting moves as well as sweet scent)

Combining horde battling with the use of specific power items and Pokerus, will make it faster and easier to obtain EVs as they heighten how many possible EVs you can get.

Calculations for EVs combined with power items/Pokerus:
Multiply by 5 for Horde encounters
Base 1 point:
Pokérus / Macho Brace: 2 EVs
Pokérus + Macho Brace: 4 EVs
Pokérus + Power Item: 10 EVs

Here's a list of hotspots:

HP
[3D='whismur']
Whismur
Location: Rusturf Tunnel
Encounter Rate: 100%
Level: 5
EVs: 1 HP each


Attack
[3D='shuppet']
Shuppet
Location: Mt. Pyre (cemetery area)
Encounter Rate: 100%
Level: 15
EVs: 1 Atk each


Defense
[3D='sandshrew']
Sandshrew
Location: Route 111
Encounter Rate: 100%
Level: 11
EVs: 1 Def each


Special Attack
[3D='oddish']
Oddish
Location: Route 119
Encounter Rate: 100%
Level: 13
EVs: 1 SpA each

[3D='spinda']
Spinda
Location: Route 113
Encounter Rate: 95%
Level: 9
EVs: 1 SpA each


Special Defense
[3D='swablu']
Swablu
Location: Route 115
Encounter Rate: 100%
Level: 10
EVs: 1 SpD each


Speed
[3D='wingull'] [3D='taillow'] [3D='zigzagoon']
Wingull, Taillow, Zigzagoon
Location: Route 104 (Northern part of route — Wingull, Southern part of route — Taillow)
Encounter Rate: 100% combined
Level: 2
EVs: 1 Spe each

[3D='zubat']
Zubat
Location: Meteor Falls
Encounter Rate: 100%
Level: 9
EVs: 1 Spe each



Sorry that this a short list, but if you want a more detailed horde training guide for Pokémon XY, check it out here.