Route 759 will bring you from Holdharbor to Fairview. It's a grassy area with few hills and cliffs. Just because there aren't much, doesn't mean you shouldn't be careful. The weather is always clear so it's a good place to relax for a picnic or to just lay down and take a nap! The Pokemon there are the ordinary with a few others ranging from geodude, Miltank, Tarous, Mareep, Flaffy, Raticate, Ponyta, and Psyduck.
Good luck, Pokemon Trainer.
Pokemon:
Geodude
Miltank
Tarous
Mareep
Flaffy
Raticate
Ponyta
Psyduck