at his gym after you8 beat team rocket at mahogony city and at radio tower
He has a Dewgong and two Seel as far as i know
Mahogany Gym
you have to beat the last gym leader
u need to push the snowballs around and find a path to her like to pryce the seventh gym leader in pokemon soulsilver and heartgold
Head to the Lake of Rage between 6:00 and 10:00.
He is at the Lake of Rage from 6am - 10am every morning.
Pryce: Seel LV 30 Piloswine LV 34 Dewong LV 32
You can battle Pryce after you defeat Team Rocket HQ. I suggest you use Fire/Electric type Pokemon, since Pryce uses both Water and Ice types
beat pryce
you cant find celebi in soulsilver
in his gym
Mewtwo can be found in Mahogany Town where Pryce is.