The pokeathlons are held in the pokeathlon dome. The pokeathlon dome is on Pokemon heartgold and soulsilver only, at the national park.
For Pokemon diamond ,pearl and platinum only, there is the contest hall in Hearthome city, where they hold Pokemon contests, where winners are awarded with a ribbon (normal rank), balloon (super rank), accessories (ultra rank) and I'm not sure about master rank. The colour or type of rank prize, differs depending on which category of contest you won under (smart=green;tough=yellow;cute=pink;beuty=blue;cool=red).A pokeathlon's prize is a badge, that has the design of pokeathlon course you won under, (speed, jump, power,skill, or stamina).
north of goldenrod
On some days of the week you can go to the pokeathon dome place in the johto region and buy on there
you can get the fire stone at the pokeathon dome (near the national park) as a prize on certain days
Shiny Stones are only available at Pokeathon Mondays,Wednesdays, Thursdays, Saturdays, and Sundays after you have obtained the National Dex.
I traded one to my game. They are common is Pokemon Diamond and Pearl, so if you get one there you can trade it to your Soul Silver. If you don't have one of these versions, you can get a Shiny Stone in the Pokeathon Dome from 3,000 BP.
north of goldenrod
To find the Pokeathon You must reach the National Park. The building before the Pokeathon. If this doesn't help lokk up a walkthrough.
you can't the spaces there are the same ones used in the pokeathon
at the pokeathon, but only on certain days
you can buy one in the pokeathon dome for 3000 points.
it's the thunder stone and at the pokeathon on wednesdays for 2000 or 2500 bp
the ones with the most big orange stars for the catagory you are doing
Once you reach Pokeathon, you can trade your points for a Dusk Stone when it is there on a certain day.
On some days of the week you can go to the pokeathon dome place in the johto region and buy on there
You can get a water stone at the Pokeathon at the prize exchange or you can get it if you come in first in the Bug catching contest.
you can get the fire stone at the pokeathon dome (near the national park) as a prize on certain days
next to the counter where two woman (one taking taking you to the pokeathon game, and one selling record cards) you need to keep going right and there will be another woman selling prizes you can get all kinds of stones for evolution such as fire stone, water stone, dawn stone, etc. for 2500 or 3000 points