Buy it with points at the Poke League thing just off of National Park
Fly to National park then just go into the pokeathlon Dome .And play games their and get points cash the points in for a thunder stone and much more.
You can buy one at pokeathlon.
Use a thunder stone
trade it over from diamond/pearl/platinum
it's the thunder stone and at the pokeathon on wednesdays for 2000 or 2500 bp
2500 points
You can find the thunder stone in New Mauville
you can find a thunder stone by checking the UNDERGROUND
black stone
you can find a dusk stone in the ruins of alpha
There is no such thing as an Ice Stone
You can get the thunder stone by going underground and digging for it in Pokemon diamond/pearl ( the thunder stone , fire stone, water stone, and the leaf stone is very rare, so good luck!).