How do you catch misdreavus in leafgreen?

In Pokémon LeafGreen, Misdreavus is not available in the wild, so you cannot catch it directly in the game. However, you can trade for a Misdreavus from Pokémon FireRed, where it can be found in the Pokémon Tower. Alternatively, you can use a Game Boy Advance link cable to trade with a friend who has FireRed to obtain Misdreavus.