Early Game (Lv. 1-20)
* Route 1: Perfect for getting your first few Pokémon up to level.
* Route 2: Slightly tougher battles, good for leveling up to the mid-teens.
* Viridian Forest: The first real challenge, with a good mix of Pokémon to train against.
* Route 22: Stronger wild Pokémon, suitable for leveling up to the high teens.
Mid-Game (Lv. 20-40)
* Route 24: Stronger Trainers and wild Pokémon, good for leveling up to the mid-thirties.
* Route 3: Provides a good mix of challenging battles, with trainers and wild Pokémon, to reach the high thirties.
* Rock Tunnel: The final push to level 40, featuring a mix of trainers and tough wild Pokémon.
Late Game (Lv. 40+)
* Power Plant: Great for grinding to the high forties, especially with the Electric-type Pokémon.
* Victory Road: A demanding gauntlet of trainers and tough wild Pokémon, ideal for training your team for the Elite Four.
* Seafoam Islands: Offers a good mix of challenging battles, with trainers and wild Pokémon.
* Cinnabar Island: The final training ground before facing the Elite Four, featuring tough trainers and strong wild Pokémon.
Important Tips for Training:
* Use Repels: Repels prevent random encounters, allowing you to focus on training against trainers.
* Utilize Exp. Share: Give this item to a Pokémon that isn't actively battling to ensure they gain experience too.
* Take advantage of Pokémon types: Train your Pokémon against opponents that are weak to their attacks for maximum experience gain.
* Use the Daycare: You can leave two Pokémon at the Daycare and they'll return with significant level-ups (and even learn moves).
Remember: These are just general recommendations. The best place to train your Pokémon will depend on your team composition and individual needs. Adjust your training strategy as needed!