Instructions
Catch a Kakuna if you don't already have one. Kakuna is found in Viridian Forest in Viridian City. It is also found on Routes 24 and 25, north and northeast of Cerulean City. Its final location is Pattern Bush on the sixth island of the Sevii Islands.
Place the Kakuna as the first Pokemon in your team. When you get into a battle, Kakuna will be the first Pokemon to come out.
Switch Kakuna out for another Pokemon when a battle begins. The only move Kakuna knows is harden. Harden is a purely defensive move, and it cannot damage an opponent.
Defeat the foe with the Pokemon you swapped for Kakuna. After the battle, experience points earned are split between this Pokemon and Kakuna.
Continue this process until Kakuna reaches Level 10. At that point, Kakuna evolves into a Beedrill.