I entered the Celadon City Gym and I battled against many Gym trainers and moved around the Gym's garden maze. I had to heal my Pokemon at the Pokemon Center again and then once I got back inside I had to roam around for a while since I got a bit lost. I eventually reached Leader Erika's place and I battled her. Her Bellossom was pretty difficult to beat for some reason, but I took it down eventually. Erika's Victreebel was also a challenge at first, but I eventually managed to strike it down with Typhlosion's Flame Wheel after swapping Pokemon. I then battled against her Jumpluff and then I earned the Rainbow Badge from her once that was done. I also got a TM from her and I saved before leaving the Gym.