I'm waiting for that too, like a sandbox version of reborn.
But you can actually change the abilities using ability capsule (using credits), as well as nature ( Celia South).
For EVs, you can buy Pidove Wings at Blackview to increase base stats. You need data chip and add password "gen2mode" to get all stats max to 252.
Whilst for IVs, would be either training at manor or use data chip and add password "fullivs" so your new pokemon have max 31 IV on all stats, so you just need to breed your favourite mons to ditto after.
Hope that helps.
