After defeating Tate and Liza, you'll need to deal with Team Aqua/Magma's plans at the Seafloor Cavern. Once the legendary Pokémon (Kyogre/Groudon) is awakened, you'll need to head to Sootopolis City. To reach Sootopolis, you'll need to use Dive (HM08) in the underwater routes around Route 126. Sootopolis City is a unique city built inside a volcanic crater. It's home to the eighth and final Gym Leader, Juan (Ruby/Sapphire) or Wallace (Emerald), who specializes in Water-type Pokémon. Water types are strong against Fire, Ground, and Rock, but weak against Electric and Grass. Before challenging the Gym, ensure your Pokémon are around Level 42-46. A strong Electric or Grass-type Pokémon will be crucial. Defeating the Gym Leader earns you the Rain Badge, allowing you to use HM07 Waterfall outside of battle, and TM03 Water Pulse.
