>>30216630Let's start from the beginning. Ash/ Red collect all of the Kanto badges and beat the Indigo league. We can infer from G/S/HG/SS that another regions' badges allow you to train Pokemon as much as you want: Both Red and Gold take their teams across Kanto and Johto, Red training his team to lvl 80+ on Mt. Silver and Gold being able to challenge the Kanto league at whatever level he wants.
