No, you do not it's in hearthome city i think close to Amity Square im not sure maybe up a little. Anyways hope this helped!
The Super Contest hall
hearthome city
if you are playing platinum she is inside
hearthome city.
You have to win the Master Rank in all categories.
Go to hearthome city in Pokemon platinum and go in the contest hall then go left and there will be pictures but you have to win the contest in 1st place and you will see yours
Same as Pokemon Diamond/Pearl. You visit the hearthome contest hall. after you have your conversation with your mom and the girl talk to the girl with the purple air to the right of the hall. If you don't know where the contest hall is, Talk to the guy in front of the first row of buildings, he will lead you there.
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.
Blend berries at a contest hall. There is a contest hall in Verdanturf, Fallarbor, Slateport and Lilycove.
If you win in the contest hall you get a ribbon but nothing else except for that
hearthome city
In Slateport City, the contest hall is close to the northern exit, just to the left of it.