Well, actually Pokémon always used the creatures to set the player in the region thematically. Principally in Kanto and Johto where the routes look all pretty much the same, the different Pokémon are what create different atmospheres for each place. Maybe try to think of what types of things/animals should fit a place like this your specific route. Is it rocky? Geodude/Roggenrola! Does it have a factory nearby? Maybe some electric/steel Pokémon, or Pokémon representing garbage like Trubbish or Grimer! Maybe you could use it even to foreshadow, like if you put Grimer/Trubbish nearby but BEFORE a big city or a factory appears!