>>31990771Other Pokemon always existed in Kanto, they just weren't discovered at that time, there were 151 KNOWN species of Pokemon in the region, when they say 'new' Pokemon, they don't mean new like we do when we get a new generation, they mean newly discovered in that region.
A medieval game wouldn't work really, how do you heal Pokemon? How do you store Pokemon in boxes without a computer? How do you do anything technical?