Cinnabar Island

Cinnabar Island is an island in Kanto. The Pokemon Mansion is here. Blaine is the Gym Leader here in Generation I and Generation III. The Pokemon Lab is here. In Gen. II, a volcano erupted leaving only the Pokemon Center and forcing Blaine to move to the Seafoam Islands. The coast on the East side is famous for the Missingno. glitch.

Generation I
TM35 Metronome

Generation II
Rare Candy

Generation III
None (though you can look inside the Pokemon Mansion)