Pokemon X & pk3DS: Editing a Trainer Pokemon's IVs/EVs

[Isol8iv]

I've been wanting to make a randomizer for X with pk3DS, and noticed that Trainer Pokemon don't seem to have a function for setting IVs individually, rather there is a value from 0 to 255 which can be set. You also don't seem to be able to set EVs or Natures at all, unlike with Ultra Moon, which I did previously. I know this has probably been asked before, but can someone explain how the IV values from 0 to 255 work, and whether there is a way to set EVs and/or Natures for Trainer Pokemon in X and Y?

Thanks, and sorry if this is, like, a really nooby question.

[Freeasabird420183]

well if you look at the pokemon in PKHeX and randomize its IV stats it gets random characteristics. just copy the IV number for the pokemon you're editing in PK3DS. and you could just ..imagine it has the characteristic you wanted due to the IV number. like if you give the Pokémon a decent IV score it does in fact get a wee bit stronger due to this then just 0 ivs like vanilla. thats how i do it anyways.