Unfortunately, you will still have to go around the winding path to reach Gym Leader Erika in the back. Her team is filled with grass-type Pokemon, and over half are a dual type. Use fire-type, ice-type, and flying-type to deal 2x damage.
Luckily the invisible walls will remain down when you revisit Koga. He will be standing in the middle of the Fuchsia Gym. His team is filled with Poison-type Pokemon. Use psychic-type or ground-type attacks to deal 2x damage.
Sabrina can be found at the back of the Saffron Gym. It’ll be a little tough to get there. Follow our custom map above.
Her team is filled with psychic-type Pokemon. Use bug-, ghost-, and dark-type attacks to deal 2x damage. Mr. Mime might be the most troublesome since he is now half fair-type and can set up Reflect and Light Screen to buff the team for five turns. They can be smashed with Brick Break, however.
Blue will take over the Viridian Gym after defeating former Leader Giovanni. His team will be upgraded and include a Mega Evolution of Charizard! This battle will be as tough as your Rival battle at the Pokemon League, so come prepared.