wtf, EVs did exist in GSC and RBY, the diff being they were called stat Exp back then. In RBYGSC, there was no limit on overall stat exp, so you can potentially max your pokemon's stats out in every stat after enough training (still controlled by genes though). iirc, each stat had a Cap of 65525 stat EXP or something, with every 2550-ish stat EXP giving you an extra stat point at lv 100. (Back then each pokemon gave stat exp to each category equal to that species' base stats)