Question

Where can my Pokemon learn Superpower in SoulSilver?

Answer 1

You can teach a Pokemon Superpower through the Move tutor in the Battle Frontier. It costs 48 Battle Points, though.

Hope I helped!

Answer 2

Battle frontier for 48 BP. Move tutor on the top right.

http://bulbapedia.bulbagarden.net/wiki/Move_Tutor