Instructions
Enter the Ice Path during the day. While Jynx appears in the morning, day and night, you have a 10 percent chance of seeing him in the day compared to five percent in morning or at night. The Ice Path is located on Route 44, just south of Mahogany Town.
Venture through the Ice Path. You have a chance of encountering Pokemon each time you take a step in the Ice Path, just like with any underground passage in the game. Although the chances of seeing Jynx are lower than seeing other Pokemon in the Ice Path, you will eventually encounter him.
Fight Jynx with a Level 20-22 Pokemon. Any Pokemon higher than that will likely do too much damage, and you may unintentionally kill Jynx before having a chance to catch her. Do not use a Fire-type Pokemon, because Jynx is considered an Ice-type, which means Fire can one- or two-shot her. Throw a Pokeball once Jynx is low on health.