longer.blue

1. Get the National Dex from Professor Oak (by capturing 60 Pokémon) 2. Go back to One Island, where Team Rocket is causing trouble again by trying to steal something (I will not spoil what this item is) 3. Then, retrieve that item, bring it to Bill's friend Celio, who will give you the Rainbow Pass to explore the other four Sevii Islands (https://bulbapedia.bulbagarden.net/wiki/Rainbow_Pass) 4. Go to Four Island, where one of the Elite Four members lives (I will not spoil this either). Team Rocket will be causing drama here too, and you have to defeat the hooligans with this Elite Four member. 5. Eventually, you will have to explore Five Island, Six Island, and Seven Island. A scientist who defected to Team Rocket will be stealing another item (I will not spoil the name of this item either) on Six Island. You will have to chase this goon back to Five Island, not before obtaining two passwords to break into Team Rocket's base on Five Island. 6. After defeating Team Rocket on Five Island and returning both items to Celio, Cerulean Cave will open, with Mewtwo in the basement. Remember, the layout is the same as Japanese Red and Green (International Red and Blue and Pokémon Yellow have different layouts) (https://bulbapedia.bulbagarden.net/wiki/Cerulean_Cave#Layout). Here is another tip, just be careful of the Wobbuffets and Electrodes due to the changes in the DV/IV and Stat EXP/EV system that led to Pokémon being frailer than they were in Gens 1 and 2 (https://bulbapedia.bulbagarden.net/wiki/Effort_values).