If you're talking about Starter Pokemon, Steven gives one of the Hoenn starters (Treecko, Torchic, and Mudkip). He'll also trade his Beldum for a Forretress.
You also talk to him in order to allow Latios/Latias to enter the game.
to find meteorites and crystals.
by pressing 'a' on it and if you have an Oran Berry, it will give it her.
you dont find it in the safari zone, yo trade steven for a foretress
You give it back & she will give you the magnet train pass.
SOulsilver
Steven isn't battleable in the game.
You can't battle Steven in Pokemon SoulSilver or HeartGold.
You don't find Steven in Mount Silver. You find Steven in Silph Co. after beating Red. He will give you a Hoenn starter.
He will give you one of the three Hoenn starters, and will also notify you of Latios' (Or LATIAS) arrival to the region.
In Saffron City
you cant beat steven in pokemon soul silver only in emerald,ruby and sapphire
no you can trade soulsilver pokemon to black
steven has to be found in the museoum in peweter city an trade pokemon with him at saffron city
to find meteorites and crystals.
Pewter museum!! :D
Unfortunately, you cannot battle Steven on Pokemon HeartGold or SoulSilver unless an event comes in the future.
from steven he'll be at sliph co. after u defeat red he will give u a choice of 1 of the 3 starters of hoenn