I believe you can buy one in Black City.
makes electric type Pokemon evolve
you have to use a thunder stone
the Pokemon that evolve with the help of a thunder stone are : pikachu +thunder stone = raichu, or eevee + thunder stone = jolteon.
You'll need to use a Thunder Stone on a Elektrik.
A worker gives it to you in Shopping Mall Nine.
thunder Pokemon if it has evolutions
You can find the thunder stone in New Mauville
you can find a thunder stone by checking the UNDERGROUND
Pickachu and eeve can evolve with the thunder stone
You can't, it needs a Thunder Stone.
thunder stone
It's in Chargestone Cave. On the first floor west of team plasma.