Ev training freshly caught Pokemon is fine. Because you won't need super training after because it will say your Pokemon is a "fully trained Pokemon" but .... If you don't like the ev's your Pokemon got... You could follow ~Crimson~'s advice and use the reset bag in super training and ev train again.
These are the Pokemon that gain ev in horde battles ( use sweet scent )
Gulpin: common , Lv 5 , in route 5 , gives 1 ev each gulpin defeated
Whismur: common, Lv 7 , in connecting cave ( cyllage city near gym ) , same ev's as gulpin
Bellsprout & Weepinbell: Both common , Bellsprout is Lv 16 and Weepinbell is Lv 24 , Bellsprout: route 14 Weepinbell: route 19 , Bellsprout gives 1 ev while Weepinbell gives 2 ev's
You can't find the Bellsprout's and its evo if it's raining so use this as a backup
Cubchoo: common , Lv 20 , frost cavern ( dendemille town go north ) , gives 1 ev each cubchoo is defeated
Nosepass: common , Lv 11 , route 10 , gives 1 ev each nosepass is defeated
Geodude & Durant: Geodude:common Durant:Uncommon , Lv 23 , G: Route 18 , D: Terminus Cave , G: 1 ev D: 2 ev's
Vanillite: common , Lv 20 , Frost Cavern , 2 ev's
( smoochum works just the same as vanillite so you can use that too )
Hoppip: common , Lv 6 , Route 7, 1 ev
Wingull: common , Lv 9 , Route 8 , 1 ev
( Tailow works the same as wingull )
You can't find wingull and Tailow when raining so here's an alternative
Zubat: common , Lv 8 , Connecting Cave m 1 ev
After you beat Elite 4, you'll gain access to Kiloude City where you can find Friend Safari. Each of your 3DS friends generates three Pokémon of one type that can be encountered there. At the beginning, you can find just two species, and a third can be found after your friend beats the Elite 4, so non-Pokémon 3DS players will give you just two Pokémon. The list of Pokémon depends on Friend Codes you have, so after you go and discover your friends' species, just check their EV yields. The best way to do this is to use Bulbapedia's or Serebii's pokedexes , as all of them list the EVs you can get from beating specific Pokémon. This method is recommended for adding smaller amounts of EVs, impossible to get via Hordes.
If you don't want to use Hordes or Friend Safari, you can try something old-fashioned. Finding random Pokémon in grass quite inconvenient, so you can try using Poke Radar to chain specific Pokémon with desired EVs. When 100% accurate encounter rates are found, I'll expand this section. For now, I need to leave you with the idea.
What if the Pokemon that you need can only be caught via using rods? Here is the list of Pokemon and their certain ev's that you can get via fishing. It's just like the others , although this time I'll put what kind of rod is needed to be used.
Corphish & Goldeen: 100% sure encounter rate , Lv 25 , route 3 , 1 ev , good rod
Magikarp & Luvdisc: 100% sure encounter rate , Lv 15 , M: route 3 , L: route 8 , 1 ev , old rod
If I put fishing ( which involves water ) why wouldn't I put surfing if it's where you can get Pokemon in the water the fastest ( unless you don't miss in your fishing ) sometimes it gets pretty annoying that you're just surfing to try and get to this place and then suddenly a wild Pokemon comes out ( you forgot to use repels ) . At least here you can make it useful by using these Pokemon to ev train. So here is the surfing version of which Pokemon gives what ev/ev's
Tentacool: very common ( not 100% but common enough ) , Lv 20-30 , route 8 , 1 ev
( you can also find wailmer but if you do just run )
Poliwhirl & Floatzel: 100% sure encounter rate ( both ) , Lv 38-40 , outside of frost cavern , 2 ev's
I can't find anything else yet but when I do I'll update this. ,but while there's still no more additional news , good luck with your ev training.