he in uknown as to where he goes, but he will come back if you beat the elite4
If you beat trainer red go to Mr Pokemon's house and he will give you a red orb.
after you beat trainer red and collect all 16 gym bagdes he is at the power plant in kanto(surf to get there).
The Legendary Trainer is the incredible bad@$$ we created in Red/FireRed. yep its red.
yes, after you beat trainer red, (ash), go to prof. oak's lab with an empty space in your party.
Beat Pokemon trainer red on top of mt silver. you can only face him once you beat all 16 gyms and the elite four twice.
if you go to your home town you can fight the trainer at your friends house once you beat the game
He vanishes.
battle your freinds that's about it :]
Steven will be in Silph Co. after you beat Trainer Red(Get all 16 Badges,Elite4) on Mount Silver. He will give you 1 or the Hoenn Starters at lvl 5.
after you beat red in Mt.silver
complete the pokedex
beat elite four rematch