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.
Buy it with points at the Poke League thing just off of National Park
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
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!).
There is no such thing as an Ice Stone