Lady, EVOLVED 
idea for a pokémon challenge run
for each route, order the pokémon available to catch in that route by pokédex number. let the number of pokémon in the route be m. let n be {your trainer ID} mod m. you can only catch the {n+1}th pokémon species available in the route
re: idea for a pokémon challenge run
@Lady why
re: idea for a pokémon challenge run
@aescling why does anyone do any challenge run
re: idea for a pokémon challenge run
@Lady @aescling i think it varies depending on the specific challenge.
tho to answer cat's question, this idea seems like its big advantages are that it would encourage one to use mons you otherwise might not by randomly shrinking the available pool of mons (as is common in e.g. nuzlockes) but without bias against infrequently-appearing mons
re: idea for a pokémon challenge run
@alyssa @aescling yeah i think “here is a somewhat limited selection of available pokémon and you have to make them work together” is interesting, but would PREFER a system that occasionally gave you “whoops, the only pokémon from dark cave you can use is the 1% encounter rate dunsparce”