If you do horde training (which is the fastest way to EV train in my opinion), here are the hordes to use:
(If you need a Sweet Scent Pokemon, just pick up an Oddish off Route 119)
HP
Whismur- Rusturf Tunnel
(1 EV for each whismur)
Attack
Shuppet- Mt. Pyre (cemetery)
(1 EV for each Shuppet)
1 Attack
Defense
Sandshrew- Route 111 (in the desert part)
(1 EV for each Sandshrew)
SP Attack
Oddish- Route 119
(1 EV for each Oddish)
SP Defense
Swablu- The far north part of Route 115
(1 EV for each Swablu)
Speed
Zigzagoon/Wingull/Taillow- Route 104 (There's a big patch of tall grass behind the Flower Shop)
(1 EV for each Pokemon)
There are more hordes than this you can use, but all of these have an appearance rate of 100% (except for the speed training on Route 104, but those are the only three hordes that will appear there anyways), so they're a bit easier to use! Hope this helped!
