you can take 3 of selected the Pokemon that you will choose before participating in the events that take place. Hopefully with reasonable capabilities their stats should coincide with how well they do in each event that takes place in the Pokeathlon dome.
For example: the Jump contest. If I went into the Jump contest, i would have to flick my stylus up to make my Pokemon jump, and do various things. The stats that your Pokemon have for jumping, coincide with how high they jump, and how far they jump.
Afterwords, if you win 1st place after getting all the points necessary, you will earn those points in a currency you can exchange for prizes. and an extra 100 points for winning first place; if you do.
If your not actually taking place in the Pokeathlon Dome, outside you can get a Apricorn Blender, and blend them into a juice. You can then feed that juice to the Pokemon you might be using inside the Pokeathlon Dome. It raises some of their stats, and sometimes can actually lower them if you use a wrong combination of apricorns on the selected Pokemon.
Chat with our AI personalities
The Pokeathlon Dome did not exist prior to Heartgold/Soulsilver, so it wasn't in Crystal.
Go to the national park and from there you should be able to the pokeathlon dome in poke mon heart gold.
On Pokemon Soul Silver and Pokemon Heart Gold, you have to defeat the Goldenrod City Gym Leader, Whitney, and then she tells you that the construction for the Pokeathlon Dome is complete.
you jump 1000 times
The Pokeathlon Dome is only in Heartgold and Soulsilver. But, there are contests in Platinum. Just go to Hearthome City and go to the northernmost part of the city to reach the contest hall.