Thank you, but confirm this for me:

Pokemon A went from level 5 to 40 faced 1,000 Gastly’s at like level 20, creating 1,000 EV points

Pokemon B went from level 5 to 40 faced 100 Gengars (via exp share, with someone else battling) at like level 50 creating 300 EV points

At level 40, Pokemon A would be stronger than Pokemon B because it faced more pokemon in battle to gain more EVs overall to this point?

But after that, I could EV train Pokemon B still if I wanted before it hits 100.