Same as in Pearl and Diamond, Pastoria City.
beside the ribbon house
I don't think you can get a Sun Ribbon in Platinum. I think its only on Mystery Dungeon.
nothing really, it just shows up in the ribbons tab on the summary of the first Pokemon you had in your partywhen you got the ribbon
nope but you can on Pokemon platinum
The effort ribbon will be given to you when the effort values (EV) of the first Pokemon in your party are full. For more info about EV's check this guide: www.gamefaqs.com/ds/946308-Pokemon-platinum-version/faqs/56146
there aren't any Pokemon inside the house
nothing really.once you get 10 ribbons on one Pokemon(i think;i have tons on my Pokemon so im not so sure) you can go in there and then buy ribbons that you can only get there or you can let the lady's massage only one Pokemon per day to make them get a higher friendship level.
In celestic town
POOPS u can liv in it
Blackthorn City in Johto. A lady in a hut will give your Pokemon the ribbon if it has worked hard.
You have to get 1 Pokemon that has I think 10 or more ribbons when you go there.
Go to Celestic town and her house is near to the left of the Pokemon center.