So, I'm kinda new here, so forgive me if this is in the wrong area.
I've just started learning to EV train, and I believe I have everything set up right, but I want to make sure before I start, so I don't have to start over.

So let's see. I'm going to train my Vanillite in SpD first. It is UT from capture, and has Macho Brace and PokeRus. If I battle a Frillish (which gives 1 SpD, I do believe) with Vanillite in front, then switch out to a high level Pokemon, does Vanillite still get the 4 SpD EV's it would have received from the Macho Brace and PKRS?
Also, I'm kinda sucky at math, so if anyone could tell me how many Frillish I would have to kill to get 252 SpD EV's if the above question is true. 4 SpD Ev's per kill would result in me having to kill 63 Frillish, correct?
And if I gave it ten of the correct vitamins to up it's SpD, that would automatically give it 100 EV's, right? So then how many Frillish would I have to kill to get 252 EV's? Would it be 38?
So with Pokerus and Macho Brace (switching in, until it's a higher level) It would take me 63 Frillish to get 252 SpD EV's. And using 10 of the SpD boosting vitamins it will take me 38 kills, correct?

Hellooo and welcome



Yep! Both pokemon will receive the EVs, so your Vanillite will receive 1 SpDef EV x2 (macho brace) x2 (PRKS) = 4 SpD, whilst your other Pokemon will receive 1 SpDef



Correcto



Make sure you feed vitamins before training though, but yes your maths is correct

Usually when I EV train (ie, almost never because I'm lazy) I take note of your move's PP - eg, say a Spark attack OHKOs Frillish. Spark has 20PP, so you know every time you deplete Spark you've defeated 20 Frillish. Saves time marking stuff down

Happy training

Another good way is getting the Stat Wings and marvelous bridge and at the drawbridge. They rase the stat by 1, and unlike vitamins were you can only use10 per stat, you can use as many wings as you want.

SO lets say you wanto give a poke 252 ivs, you give it 10 Hp- ups, now it needs 152 Evs. IF you have 152 health wings, your set. Of course it does take a long time to gather up the wings.