>>39137226A truly open world pokemon game similar in style to botw would have to entirely rethink its exp and lvl system, and thus a majority of evolutions as well. Far from impossible but definitely a difficult shift to make
You could possibly implement a less shit version of pokemon go's powerup mechanics. The team's growth is dependent upon the trainer's experience and strength, increased with badges or something of the sort.
And if you wanted to travel across multiple regions, you could force team rotation through local trainer laws that only permit you to wield pokemon of certain strengths based on your reputation in the region.
Of course members of evil teams would disobey such laws, and any chance encounter with one of them is a gamble as they could have a super fucking beefed team in an area youd expect to see low level trainers