Pokemon Storm Silver - Boss #58 - Champion Steven
In order to fight Steven, you have to go through the sequence of getting the Clefairy doll in Vermilion City to get the Magnet Train Pass. Then you go to Azalea Town's Pokemon Center to do a quiz to get one of the Hoenn starters. Then you go back to Steven to show him that starter and then you have to catch Latios who roams around in Kanto randomly. Then you show him Latios and then Steven will give you the Enigma Stone. You give this stone to the archeoligist next to Cynthia, which will let him give you the Soul Dew. With the Soul Dew you can open up the capsule where Latias is hidden inside. Then you go back to Steven to then go to Mt. Silver while having Regirock, Regice and Registeel in your party (which you'd catch in Ice Cave, Mt. Mortar and Dark Cave) to battle Regigigas. And finally when that's done, Steven will battle you.