Well, choice one is save yourself a huge amount of trouble and just give it to 4th gen. But...honestly I never EV trained in Leaf Green, Kanto doesn't have many good hotspots that I can think of, besides Ghastly for Special Attack and Pidgey/Rattata for Speed. I want to say Victory Road with Machop and Machoke or fishing Goldeen is probably the best bet in Kanto. Not sure about trainers.
I did all of my EV training in Hoenn or Shinnoh, so if you want to know about them, I'm your man to ask. :P