The eighth and final Gym Leader you will face on the road to collecting all eight Kanto Gym Badges is Giovanni, the leader of Team Rocket. He is the Viridian City Gym Leader, specializing in Ground Type Pokemon. Since you are nearing the end of collecting all eight Kanto Gym Badges, Giovanni's Pokemon Team will be extremely difficult to defeat. However, if you did pick Bulbasaur or Squirtle as your Starter Pokemon, you will have the clear advantage over Giovanni since he is especially weak against both Grass Types and Water Types.
If you happened to choose Charmander as your Starter Pokemon, you will probably need to add an additional Pokemon or two to better help you with Giovanni's (two) Rhyhorn, Dugtrio, Nidoqueen and Nidoking. Luckily, you will come across loads of Water Type Pokemon while surfing to and from Cinnabar Island, the same that can be captured in order to help you defeat Giovanni. You can even fish in those same waters to catch even more Water Type Pokemon!
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