Instructions
Catching Johto Pokemon on the Sevii Islands
Defeat Blaine at the gym on Cinnabar Island. After you exit the gym you can speak with Bill at any time to travel to the Sevii Islands. However, you will be restricted to the first three islands for the time being.
Capture more than 60 Pokemon, then defeat the Elite Four and continue your game once the credits have finished rolling.
Speak with Professor Oak. After taking you to his lab, Professor Oak gives you the National Dex, which contains data for all Pokemon rather than only the original 151 Pokemon. This will allow you to capture Johto Pokemon.
Travel to Sevii Island One and speak with Celio. He will give you the Tri-Island pass, which allows you to visit all seven islands. You may now go to any island and attempt to catch as many Johto Pokemon as you like, including the legendary Moltres at the top of the mountain on the first island.
The Legendary Beast
Establish which legendary Johto Pokemon appears by your choice of starter Pokemon. Choose Bulbasaur as your starter to make Entei appear. Choose Charmander as your starter for Suicune to appear. Choose Squirtle as your starter for Raikou to appear.
Defeat the Elite Four. Afterward there is a chance to encounter a legendary Johto Pokemon in the wild. You will know that you have encountered your legendary opponent if the battle music is different from normal and if your opponent is much larger than usual.
Catch the legendary beast using a Master Ball.
Weaken the beast with sleep, paralysis or another status effect if you do not have a Master Ball. However, be careful to not kill the beast; you will not have another chance to catch the beast if you kill it. You can also use False Swipe to weaken the beast, because this attack will always leave your opponent with at least one hit point.