I had to check rn just to be sure, and it turns out, I was not gaining EVs despite killing pokemon. This shouldn't have been the case as the intention was for exp gain to be done like it is for level 100's, who despite not gaining exp, do gain EV's upon killing pokemon in reborn. I've changed the script accordingly and now properly get EVs, though this does make me want to revise some of my lategame strats that did use EV's to see if I can do them without.
As for Lategame team, most of the wild pokemon by lategame come at levels 80-90, and at levels that high, it doesn't matter too much if the levels rise to say 90+ or 100. By that point, level gap hardly matters at all, and what does matter is EV's, IV's, items, natures, what moves i have available etc.
Very glad this remark came up so that I could fix this issue and remind me to see if I can EV proof this run.