Jasmine is the kindhearted and helpful Steel-Type Gym Leader in Gold, Silver and Crystal that you help when curing the sick Ampharos in the Olivine City Lighthouse. She loves all Steel Type Pokémon, and whilst battling her the new evolution of Onix is revealed.
 Anime Appearances
Jasmine first appears in the episode Fight for the Light, where, in a parallel to the video games, needs medicine that is made in Cianwood City in order to heal a sick Ampharos that provides power to the Olivine City Lighthouse.
Jenina, one of Jasmine's students, returns to Olivine City with that medicine in the episode Machoke, Machoke Man, setting the stage for Ash's gym battle with Jasmine in the episode Nerves of Steelix.
Ash's Pikachu defeated Jasmine's Magnemite for the first fall in a 2-on-2 match. Jasmine's second Pokémon Steelix defeated Pikachu to even the match. Cyndaquil had its hands full with Jasmine's Steelix, but Cyndaquil would eventually overcome the Iron Snake Pokémon to win the match and the Mineral Badge.
Jasmine made an appearance during the Sinnoh Saga as well, appearing in the episode Four Roads Diverged in a Pokémon Port. Her Steelix participated in a training battle against Flint and his Infernape, a one-on-one battle that Infernape emerged with the victory.
Related ThreadsHow do I get Jasmine to trade her Steelix? - last post by @ Jan 22, 2014
can't get Jasmine's PokeGear number - last post by @ Oct 8, 2011
Steelix from Jasmine Questions - last post by @ Nov 5, 2010
battle jasmine - last post by @ Apr 3, 2010
What level were your pokemon when you were at Jasmine's battle point. - last post by @ Aug 31, 2013